Method, system, and computer readable medium for detecting related subgroups of text in an electronic document

ABSTRACT

Disclosed herein are systems and methods for navigating electronic texts. According to an aspect, a method may include determining that a user non-linearly navigates between text subgroups within electronic text. The method may also include linking the text subgroups in response to determining that the user non-linearly navigates between the text subgroups. Further, for example, text subgroups within an electronic text may be determined. In this example, a similarity relationship between content of each text subgroup and one or more other text subgroups may be determined for linking the text subgroups.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional patentapplication no. 61/387,718, filed Sep. 29, 2010, the content of which ishereby incorporated herein by reference in its entirety. Further, thisapplication is related to co-pending U.S. utility patent applicationSer. No. 13/239,360, filed simultaneously herewith and titled “METHOD,SYSTEM, AND COMPUTER READABLE MEDIUM FOR CREATING CLUSTERS OF TEXT IN ANELECTRONIC DOCUMENT,”and U.S. utility patent application Ser. No.13/239,363, filed simultaneously herewith and titled “METHOD, SYSTEM,AND COMPUTER READABLE MEDIUM FOR GRAPHICALLY DISPLAYING RELATED TEXT INAN ELECTRONIC DOCUMENT,” all of which are hereby incorporated herein byreference in their entireties.

TECHNICAL FIELD

The present disclosure relates to systems and methods for navigatingelectronic texts.

BACKGROUND

Electronic books, or e-books, are text and image-based publications indigital form produced on, published by, and readable on computers orother electronic devices. E-books are often read on dedicated hardwaredevices, such as e-book readers or e-book devices. Personal computers,mobile devices, such as smart phones, and other suitable devices mayalso be used for reading e-books.

Often, while reading a long or complicated electronic text in an e-book,a user may lose track of previous plot elements or may forget aboutcharacters or objects. This problem may be worse for lengthy storiesthat span a series of novels, since plot elements and entities fromprevious entries in the series can frequently influence development insubsequent novels. For at least this reason, it is desired to providesystems and methods for aiding users when navigating electronic texts.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter.

Disclosed herein are systems and methods for navigating electronictexts. According to an aspect, a method may include determining that auser non-linearly navigates between text subgroups within electronictext. The method may also include linking the text subgroups in responseto determining that the user non-linearly navigates between the textsubgroups.

According to another aspect, a method may include determining a currentuser position within an electronic text. The method may also includedetermining a current text subgroup corresponding to the current userposition. Further, the method may include displaying in a first displayarea, a portion of the electronic text corresponding to the current textsubgroup. The method may also include displaying in a second displayarea, one or more related text subgroups positioned before the currenttext subgroup. Further, the method may include displaying in a thirddisplay area, one or more related text subgroups positioned after thecurrent text subgroup.

According to another aspect, a method may include determining textsubgroups within an electronic text. The method may also includeselecting a text seed within one of the text subgroups. Further, themethod may include determining a similarity relationship (e.g., asemantic relationship) between the text seed and one or more adjacenttext subgroups that do not include the selected text seed. The methodmay also include associating the text seed with the one or more adjacenttext subgroups based on the similarity relationship to create a textcluster.

According to another aspect, a method may include determining textsubgroups within an electronic text based on a similarity relationship(e.g., a semantic relationship) of content within each text subgroup.The method also includes determining, for each text subgroup, anothersimilarity relationship between content of the text subgroup and one ormore other text subgroups. Further, the method may include linking, foreach text subgroup, the text subgroup to the one or more other textsubgroups based on the other similarity relationship.

According to another aspect, a method may include receiving searchcriteria for searching an electronic text. Further, the method mayinclude determining text subgroups within the electronic text. Themethod may also include determining, for each text subgroup, asimilarity relationship between the search criteria and the textsubgroup. Further, the method may include presenting, for each textsubgroup, a graphic representing the similarity relationship between thetext subgroup and the search criteria.

According to another aspect, a method may include determining textsubgroups within an electronic text based on a similarity relationship(e.g., a semantic relationship) of content within each text subgroup.The method also includes determining, for each text subgroup, anothersimilarity relationship between content of the text subgroup and one ormore other text subgroups. Further, the method may include linking, foreach text subgroup, the text subgroup to the one or more other textsubgroups based on the other similarity relationship.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofpreferred embodiments, is better understood when read in conjunctionwith the appended drawings. For the purposes of illustration, there isshown in the drawings exemplary embodiments; however, the presentdisclosure is not limited to the specific methods and instrumentalitiesdisclosed. In the drawings:

FIG. 1A is a schematic diagram of a system including e-book readers andan e-book server according to embodiments of the present disclosure;

FIG. 1B is a schematic diagram of a system including an e-book readerand an e-book server according to embodiments of the present disclosure;

FIG. 2 is a front view of an e-book reader displaying content of ane-book via its display in accordance with embodiments of the presentdisclosure;

FIG. 3 is a flow chart of an exemplary method for providing a link fornavigating an electronic text in accordance with embodiments of thepresent disclosure;

FIG. 4 is a flow chart of an exemplary method for linking text subgroupswithin an electronic text for use in navigating the electronic text inaccordance with embodiments of the present disclosure;

FIG. 5 illustrates a flow chart of an exemplary method for graphicallyrepresenting similarity relationships between text subgroups within anelectronic text in accordance with embodiments of the presentdisclosure;

FIG. 6 illustrates a flow chart of an exemplary method of analyzing usernavigation of an electronic text for linking text subgroups within theelectronic text in accordance with embodiments of the presentdisclosure;

FIG. 7 illustrates a flow chart of an exemplary method of controlling auser interface to display text subgroups that are related to a currentposition of a user within an electronic text in accordance withembodiments of the present disclosure;

FIG. 8 illustrates a front view of an e-book reader displaying a portionof an electronic text within a display area in accordance withembodiments of the present disclosure;

FIG. 9 illustrates a flow chart of an exemplary method of clusteringtext within an electronic text based on a similarity relationshipbetween adjacent sentences in accordance with embodiments of the presentdisclosure;

FIG. 10 illustrates a diagram depicting a clustering process for anelectronic text in accordance with embodiments of the presentdisclosure;

FIG. 11 illustrates a flow chart of an exemplary method of assigningforward and backward links for each text cluster of an electronic textin accordance with embodiments of the present disclosure;

FIG. 12 illustrates the diagram shown in FIG. 10 in which a process forlinking a text cluster is implemented in accordance with embodiments ofthe present disclosure;

FIG. 13 illustrates the diagram shown in FIGS. 10 and 12 in which alllinks for all text clusters have been completed in accordance withembodiments of the present disclosure;

FIG. 14 illustrates a diagram depicting a heat map of an e-book inaccordance with embodiments of the present disclosure;

FIG. 15 depicts diagrams of heat maps for hierarchical navigation of ane-book in accordance with embodiments of the present disclosure;

FIG. 16 illustrates a message flow diagram of an exemplary operation ofthe system shown in FIG. 1 in accordance with embodiments of the presentdisclosure;

FIG. 17 is a block diagram of the e-book reader shown in FIG. 1according to embodiments of the present disclosure; and

FIG. 18 is a block diagram of the e-book server shown in FIG. 1according to embodiments of the present disclosure.

DETAILED DESCRIPTION

The present disclosure is described with specificity to meet statutoryrequirements. However, the description itself is not intended to limitthe scope of this patent. Rather, the inventors have contemplated thatthe claimed subject matter might also be embodied in other ways, toinclude different steps or elements similar to the ones described inthis document, in conjunction with other present or future technologies.Moreover, although the term “step” may be used herein to connotedifferent aspects of methods employed, the term should not beinterpreted as implying any particular order among or between varioussteps herein disclosed unless and except when the order of individualsteps is explicitly described.

Embodiments of the present disclosure enable an electronic device, suchas an e-book reader, to determine text subgroups within an electronictext, to select a text seed within one of the text subgroups, todetermine a similarity relationship (e.g., a semantic relationship)between the text seed and one or more adjacent text subgroups that donot include the identified text seed, to associate the text seed withthe one or more adjacent text subgroups based on the similarityrelationship to create a text cluster, and to link the text cluster toanother one of the text subgroups within the electronic text based on asimilarity relationship between the text cluster and the other one ofthe text subgroups. For example, text subgroups may include, but are notlimited to, chapters, paragraphs, sentences, and the like. Further, forexample, a text seed may include one or more words and the like. Thetext seed may be selected based on a relevance or similarity scoreassigned to words of the electronic text. The similarity relationshipbetween the text seed and adjacent text subgroups may be determined by,for example, but not limited to, performing semantic analysis,performing natural language processing, using methods such astokenization, sentence segmentation, parts-of-speech tagging, namedentity recognition, stemming, lemmatization, co-reference resolution,parsing, relation extraction, vector space models, latent semanticanalysis, and the like, identifying causal relationships between thetext seed and the text subgroups, determining semantic similarity basedon ontology, using a semantic index to compare semantic similarities,determining a statistic similarity, the like, and combinations thereof.Similar or related text subgroups may be combined to form text clustersof similar content. Subsequently, similar text clusters may then belinked together by, for example, navigation links. In this way and asdescribed in further detail herein, portions of the electronic text thatare semantically related may be linked together such that a user mayselect a portion of the electronic text and become directed to one ormore semantically-relevant portions.

In other embodiments of the present disclosure, an electronic device isenabled to determine text subgroups within an electronic text based on asimilarity relationship of the content within each text subgroup.Further, for each text segment, the electronic device may determineanother similarity relationship between content of the text subgroup andone or more other text subgroups, and link the text subgroup to the oneor more other text subgroups based on the other similarity relationship.

In other embodiments of the present disclosure, an electronic device isenabled to receive search criteria for searching an electronic text, andto determine text subgroups within electronic text. Further, for eachtext subgroup, the electronic device may determine a similarityrelationship between the search criteria and the text subgroup, andpresent a graphic representing the similarity relationship between thetext subgroup and the search criteria. For example, a user may selectone or more passages and/or one or more keywords of electronic text foruse in presenting a graphic representing a relationship between thepassage(s) and/or keyword(s) and other portions of the electronic text,and for use in navigating directly to one or more other related portionsof the electronic text.

In other embodiments of the present disclosure, an electronic device isenabled to determine that a user non-linearly navigates between textsubgroups within an electronic text, and to link the text subgroups inresponse to determining that the user non-linearly navigates between thetext subgroups.

In other embodiments of the present disclosure, an electronic device isenabled to determine a current user position within an electronic text,to determine a current text subgroup corresponding to the current userposition, to display a portion of the electronic text corresponding tothe current text subgroup in a first display area, to display one ormore related text subgroups or navigation links to the related textsubgroups in a second display area. In another embodiment, the relatedtext subgroups may be divided into two subsets based on whether therelated text groups are positioned before the current text subgroup orafter, and the device is enabled to display one or more related textsubgroups positioned before the current text subgroup in a seconddisplay area, and to display one or more related text subgroupspositioned after the current text subgroup in a third display area.

As referred to herein, the term “electronic device” should be broadlyconstrued. It can include any type of device capable of presentingelectronic text to a user. For example, the electronic device may be ane-book reader configured to present an e-book to a user. Example e-bookreaders include, but are not limited to, the KINDLE® and NOOK® e-bookreaders. In another example, an electronic device may be a mobile devicesuch as, for example, but not limited to, a smart phone, a cell phone, apager, a personal digital assistant (PDA, e.g., with GPRS NIC), a mobilecomputer with a smart phone client, or the like. An electronic devicecan also include any type of conventional computer, for example, adesktop computer or a laptop computer. A typical mobile device is awireless data access-enabled device (e.g., an iPHONE® smart phone, aBLACKBERRY® smart phone, a NEXUS ONE™ smart phone, an iPAD® device, orthe like) that is capable of sending and receiving data in a wirelessmanner using protocols like the Internet Protocol, or IP, and thewireless application protocol, or WAP. This allows users to accessinformation via wireless devices, such as smart phones, mobile phones,pagers, two-way radios, communicators, and the like. Wireless dataaccess is supported by many wireless networks, including, but notlimited to, CDPD, CDMA, GSM, PDC, PHS, TDMA, FLEX, ReFLEX, iDEN, TETRA,DECT, DataTAC, Mobitex, EDGE and other 2G, 3G, 4G and LTE technologies,and it operates with many handheld device operating systems, such asPalmOS, EPOC, Windows CE, FLEXOS, OS/9, JavaOS, iOS and Android.Typically, these devices use graphical displays and can access theInternet (or other communications network) on so-called mini-ormicro-browsers, which are web browsers with small file sizes that canaccommodate the reduced memory constraints of wireless networks. In arepresentative embodiment, the mobile device is a cellular telephone orsmart phone that operates over GPRS (General Packet Radio Services),which is a data technology for GSM networks. In addition to aconventional voice communication, a given mobile device can communicatewith another such device via many different types of message transfertechniques, including SMS (short message service), enhanced SMS (EMS),multi-media message (MMS), email WAP, paging, or other known orlater-developed wireless data formats. Although many of the examplesprovided herein are implemented on an e-book reader, the examples maysimilarly be implemented on any suitable electronic device, such as acomputer or smart phone.

As referred to herein, the term “electronic text” should be broadlyconstrued. For example, an electronic text can reside on an electronicdevice. Example text can be presented and stored in the form of bookpages that may be browsed using an electronic device. The text may bestored in any suitable format, such as, but not limited to, portabledocument format (PDF), hypertext markup language (HTML), extensiblemarkup language (XML), EPUB, or any suitable e-book or word processingformat.

As referred to herein, a “user interface” (UI) is generally a system bywhich users interact with an electronic device. An interface can includean input for allowing users to manipulate an electronic device, and caninclude an output for allowing the system to present information (e.g.,e-book content) and/or data, indicate the effects of the user'smanipulation, etc. An example of an interface on an electronic deviceincludes a graphical user interface (GUI) that allows users to interactwith programs in more ways than typing. A GUI typically can offerdisplay objects, and visual indicators, as opposed to text-basedinterfaces, typed command labels or text navigation to representinformation and actions available to a user. For example, an interfacecan be a display window or display object, which is selectable by a userof a mobile device for interaction. The display object can be displayedon a display screen of an electronic device and can be selected by andinteracted with by a user using the interface. In an example, thedisplay of the electronic device can be a touch screen, which candisplay the display icon. The user can depress the area of the displayscreen at which the display icon is displayed for selecting the displayicon. In another example, the user can use any other suitable interfaceof a mobile device, such as a keypad, to select the display icon ordisplay object. For example, the user can use a track ball or arrow keysfor moving a cursor to highlight and select the display object.

Operating environments in which embodiments of the present disclosuremay be implemented are also well-known. In a representative embodiment,a mobile electronic device, such as an e-book reader, is connectable(for example, via WAP) to a transmission functionality that variesdepending on implementation. Thus, for example, where the operatingenvironment is a wide area wireless network (e.g., a 2.5G network, a 3Gnetwork, or a 4G network), the transmission functionality comprises oneor more components such as a mobile switching center (MSC) (an enhancedISDN switch that is responsible for call handling of mobilesubscribers), a visitor location register (VLR) (an intelligent databasethat stores on a temporary basis data required to handle calls set up orreceived by mobile devices registered with the VLR), a home locationregister (HLR) (an intelligent database responsible for management ofeach subscriber's records), one or more base stations (which provideradio coverage with a cell), a base station controller (BSC) (a switchthat acts as a local concentrator of traffic and provides localswitching to effect handover between base stations), and a packetcontrol unit (PCU) (a device that separates data traffic coming from amobile device). The HLR also controls certain services associated withincoming calls. Of course, embodiments in accordance with the presentdisclosure may be implemented in other and next-generation mobilenetworks and devices as well. The mobile device is the physicalequipment used by the end user, typically a subscriber to the wirelessnetwork. Typically, a mobile device is a 2.5G-compliant device,3G-compliant device, or 4G-compliant device that includes a subscriberidentity module (SIM), which is a smart card that carriessubscriber-specific information, mobile equipment (e.g., radio andassociated signal processing devices), a user interface (or aman-machine interface (MMI)), and one or more interfaces to externaldevices (e.g., computers, PDAs, and the like). The electronic device mayalso include a memory or data store.

The presently disclosed subject matter is now described in more detail.For example, FIG. 1A illustrates a schematic diagram of a system 100including e-book readers 102 and 104 and an e-book server 106 accordingto embodiments of the present disclosure. Referring to FIG. 1A, thee-book readers 102 and 104 may be any type of electronic devices capableof presenting an electronic text, such as an e-book, to a user. Thee-book readers 102 and 104 comprise a number of functional components.This representation of the e-book readers 102 and 104 is meant to be forconvenience of illustration and description, and it should not be takento limit the scope of the present disclosure as one or more functionsmay be combined. Typically, these components are implemented in software(as a set of process-executable computer instructions, associated datastructures, and the like). One or more of the functions may be combinedor otherwise implemented in any suitable manner (e.g., in hardware, infirmware, in combined hardware and software, or the like). The e-bookreaders 102 and 104 may each include an electronic text manager 108 formanaging storage of one or more electronic texts in respective datastores 110 and for controlling presentation of an electronic text to auser. The e-book readers 102 and 104 may each include a user interface112 capable of receiving user input and of presenting an electronic textto a user. For example, the user interface 112 may include a displaycapable of displaying an e-book to a user. The data stores 110 may be asuitable memory device.

The e-book readers 102 and 104 may also be capable of communicating witheach other, the e-book server 106, and other devices. For example, thee-book readers 102 and 104 may each include a network interface 114capable of communicating with the e-book server 106 via a network 116,such as the Internet, such as a wireless network, local area network(LAN), or any other suitable network. In another example, the e-bookreaders 102 and 104 can be Internet-accessible and can interact with thee-book server 106 using Internet protocols such as HTTP, HTTPS, and thelike.

The operation of the e-book reader 102 can be described by the followingexample. As shown in FIG. 1A, the e-book reader 102 includes variousfunctional components and the data store 110 to facilitate theoperation. The operation of the disclosed methods may be implementedusing components other than as shown in FIG. 1A. In an alternativeembodiment, this example operation may be suitably implemented by anyother suitable electronic device, such as, but not limited to, a serveror other electronic device having at least a processor and a memory.

In an example, a user of the e-book reader 102 may use an application(often referred to as an “app”) residing on the e-book reader 102 tointeract with an e-book 118 stored in the data store 110. Theapplication may reside on the e-book reader 102 and be a part of theelectronic text manager 108. The user may, for example, input commandsinto the user interface 112 for opening the e-book 118 and forinteracting with the e-book 118. The application may present text and/orimages of the e-book 118 to the user via a display of the user interface112. For example, FIG. 2 illustrates a front view of an e-book reader102 displaying content of an e-book via its display 200 in accordancewith embodiments of the present disclosure. In this example, the display200 is a touch screen display. The user may suitably interact with thee-book reader 102 to control the display of different portions of thee-book's content. For example, the user may touch the display 200, suchas by use of a “swiping” motion on the surface of the display 200, tocommand the electronic text manager 108 to “turn” pages of the e-book aswill be understood. The user may turn or otherwise select pages fordisplay by any other suitable technique as will be understood. Asdescribed in further detail herein, selection of a portion of thecontent of the e-book, such as by touching a portion of text displayedby the e-book, may be interpreted as input for semantic navigation to arelated portion of the e-book in accordance with embodiments of thepresent disclosure.

In accordance with embodiments of the present disclosure, the user ofthe e-book reader 102 may interact with the display 200 to select one ormore portions of displayed content of the e-book for initiating semanticnavigation based on the selected portion(s). In an example, the user mayinteract with the display 200 for selecting a displayed phrase 202.Selection of the phrase 202 may be verified to the user by any suitabletechniques such as by highlighting or bolding the letters or othercharacters in the phrase 202. The user may select a portion of thee-book by touching or swiping a desired portion of the e-book displayedto the user. For example, the user may touch or swipe a word, one ormore paragraphs, or the entirety of a displayed page for selecting thatportion of the display. The electronic text manager 108 may receiveidentification of the selected portion and, in response, navigate to arelevant position within the e-book as described in further detailherein.

In accordance with embodiments of the present disclosure, FIG. 3illustrates a flow chart of an exemplary method for providing a link fornavigating an electronic text. The method of FIG. 3 is described withrespect to the example e-book reader 102 shown in FIGS. 1 and 2,although the method may be implemented by any suitable system orelectronic device. The steps of FIG. 3 may be implemented entirely, orin part, by the electronic text manager 108 residing on the e-bookreader 102 shown in FIG. 1A. The electronic text manager 108 may beimplemented by software, hardware, firmware, or combinations thereof.

Referring to FIG. 3, the method includes determining text subgroupswithin an electronic text (step 300). For example, the electronic textmanager 108 may access the text and/or metadata of the e-book 118 andmay identify text subgroups within the text based on the text and/ormetadata. For example, the electronic text manager 108 may identifychapters, paragraphs, and sentences within the e-book 118. Theelectronic text manager 108 may suitably identify such text subgroupsbased on punctuation, headings, and other indicators contained in thetext of the e-book 118 or by using natural language processing methods.In another example, an e-book may include metadata that identifies textsubgroups, such as the beginning and ending of each chapter within thee-book.

The method of FIG. 3 includes selecting a text seed within one of thetext subgroups (step 302). A text seed within a text subgroup may beselected based on its determined relevance. For example, the electronictext manager 108 may determine a relevance score for each word withinthe e-book 118. The electronic text manager 108 may determine the wordfrequency, or term frequency, for each word. For each word, theelectronic text manager 108 may determine a word weighting by dividingthe term frequency by the “inverse document frequency,” which may bedetermined by counting the number of times a word occurs in multipledocuments and the number of documents in which each word occurs. In oneembodiment, instead of, or along with, the inverse document frequency,an “inverse segment frequency” may be used, which may be determined bycounting the number of segments, such as chapters or paragraphs withinthe current document, in which a word occurs. Words corresponding topersons, places, or things occurring in the e-book may be givenadditional weighting. A relevance score for the word may be assignedbased on the word weighting for the word. The electronic text manager108 may choose the text seed based on the relevance score. In anotherembodiment, the text seed may also be selected based on its positionwithin the text, or randomly, for instance if there are multiple textseeds with similar word weighting-based relevance scores. In thisexample, the selected text seed may be one of the words having one ofthe highest relevance scores.

The method of FIG. 3 includes determining a similarity relationshipbetween the text seed and one or more adjacent text subgroups that donot include the selected text seed (step 304). This step may initiate aprocess herein referred to as “clustering” by which similar textsubgroups are associated with one another to create a “text cluster.” Atext cluster may include a grouping of words, sentences, paragraphs,chapters, and the like that have been deemed relevant and that arepositioned adjacent or near each other in the electronic text. Multipletext seeds may be selected within the electronic text for creatingmultiple text clusters as described herein. In an example of using atext seed to create a text cluster, the electronic text manager 108 maydetermine a similarity score between a text seed and sentences (or otherportions of the electronic text) immediately before and immediatelyafter the text seed. If the text seed is separated from a sentence by,for example, a paragraph break or chapter break, the similarity scoremay be penalized or reduced by a predefined value. Such penalties may beapplied across breaks, because it is likely that subject matter willchange across paragraphs and chapters.

The method of FIG. 3 includes associating the text seed with the one ormore adjacent text subgroups based on the similarity relationship tocreate a text cluster (step 306). For example, a text seed may beassociated with the adjacent text subgroup having the highest similarityscore to create a text cluster. The text cluster may then be compared toother portions of the electronic text immediately before and immediatelyafter the text cluster. The electronic text manager 108 may determine asimilarity score between the text cluster and sentences (or otherportions of the electronic text) immediately before and immediatelyafter the text cluster. If the text cluster is separated from a portionof the electronic text by, for example, a paragraph break or chapterbreak, the similarity score may be penalized or reduced by a predefinedvalue. The similarity score may also be penalized if the size of theresulting text cluster is overly large, for instance, if it crosses acertain size threshold. The sentence having the highest similarity scoremay be added to the text cluster to form a modified text cluster.Multiple text clusters may be added to in this manner until all textsubgroups in the electronic text have been added to a text cluster.

The method of FIG. 3 includes linking the text cluster to another one ofthe text subgroups within the electronic text based on a similarityrelationship between the text cluster and the other one of the textsubgroups (step 308). For example, the electronic text manager 108 maydetermine a similarity score between the text cluster and other textclusters within the electronic text. It is noted that clusters maycontain one or more text subgroups. The electronic text manager 108 maydetermine a highest similarity score among the determined similarityscores. Subsequently, the electronic text manager 108 may link the textcluster to the text subgroup (or other text cluster) having the highestsimilarity score. When the electronic text is opened for presentation toa user, for example, a user interface of an e-book reader may present anavigational link that links the text cluster to the linked-to textsubgroup. In this way, when a portion of the text cluster is presentedto a user, the user may select the navigational link for navigating tothe related, linked-to text subgroup.

In some embodiments, the text clusters generated by the clusteringalgorithm may overlap in part with text clusters before and after it.This differs from other methods of text segmentation in the art, whereinsegments do not overlap as they are meant to each represent a sub-topic,subject or a discussion of a sub-topic in itself. However, the method ofFIG. 3 described above that incrementally clusters text subgroups, suchas sentences, into text clusters by comparison with a seed text mayresult in overlapping clusters. This may happen, for example whenmultiple relevant topics or subjects are discussed within a passage, andsubsequent passages continue discourse on only a subset of the subjectsof previous passages. Here, the overlap in adjacent clustered textclusters would include subjects or topics that are common to both textclusters. Note that, however, the overlap in text clusters may be purelyfor the purposes of organization and generation of navigation links, andmay not reflect in the user interface, that is, it may not result inrepeated display of text to users. In an embodiment, the seed-basedclustering algorithm may be applied recursively on the text clusters ithas generated, thereby further generating text sub-clusters within eachtext cluster. Each text sub-cluster may include one or more textsubgroups within a text cluster. For example, each subset of subgroupswithin a text-cluster relating to a different subset of sub-topics inthe larger text cluster may be clustered into a text sub-cluster. Theserecursively generated sub-clusters may have a hierarchical structure,and hence may be stored as hierarchical records and may enablehierarchical navigation or navigation based on varying levels of detail.For instance, when a user elects to navigate from a current textcluster, a top-level related text cluster may be found based on semanticand contextual matching with the current top-level text cluster, and amore specific related text sub-cluster or individual text subgroup maybe found within the top-level text cluster by further semantic andcontextual matching with the sub-cluster in the current top-level textcluster at which the user is positioned, or the specific text in thecurrent text cluster selected by the user.

FIG. 1B illustrates a schematic diagram of a system 132 including ane-book reader 102 and an e-book server 134 according to embodiments ofthe present disclosure. Referring to FIG. 1B, the e-book server 134 mayinclude an electronic text manager 108 configured to determine textsubgroups within an electronic text, select a text seed within one ofthe text subgroups, determine a similarity relationship between the textseed and one or more adjacent text subgroups that do not include theselected text seed, and associate the text seed with the one or moreadjacent text subgroups based on the similarity relationship to create atext cluster in accordance with embodiments of the present disclosure.Further, the electronic text manager 108 may also link the text clusterto another one of the text subgroups within the electronic text based ona similarity relationship between the text cluster and the other one ofthe text subgroups.

In an embodiment, the e-book reader 102 may include a client application136 for facilitating interaction with the e-book server 134. The clientapplication 136 may be implemented by software, hardware, firmware, orcombinations thereof. A user of the e-book reader 102 may initiate theclient application 136 for selection of the e-book 118 for navigation inaccordance with embodiments of the present disclosure. In response tothe selection, all or a portion of the e-book 118 may be communicated tothe e-book server 134 for determining text subgroups within the e-book118, selecting a text seed within one of the text subgroups, determininga similarity relationship between the text seed and one or more adjacenttext subgroups that do not include the selected text seed, andassociating the text seed with the one or more adjacent text subgroupsbased on the similarity relationship to create a text cluster. Further,the e-book server 134 may link the text cluster to another one of thetext subgroups within the e-book 118 based on a similarity relationshipbetween the text cluster and the other one of the text subgroups. Textsubgroup information, similarity relationship, text cluster, and/or linkinformation may be communicated by the e-book server 134 to the e-bookreader 102. This information may be used by the electronic text manager108 of the e-book reader 102 for assisting the user to navigate the textof the e-book 118 in accordance with embodiments of the presentdisclosure. For example, when the e-book 118 is opened for presentationto the user, the user interface 112 may present one or more navigationallinks that links a text cluster to the linked-to text subgroup. Inaccordance with embodiments of the present disclosure, the e-book server134 may implement this functionality either alone or in combination withthe e-book reader 102.

The e-book server 134 may also be configured to suitably implementembodiments of other methods, processes, or functions disclosed herein.For example, the e-book server 134, either alone or in combination withthe e-book reader 102, may be configured to implement the examplemethods of FIGS. 4-7, 9, and 11.

In accordance with embodiments of the present disclosure, FIG. 4illustrates a flow chart of an exemplary method for linking textsubgroups within an electronic text for use in navigating the electronictext. The method of FIG. 4 is described with respect to the examplee-book reader 102 shown in FIGS. 1 and 2, although the method may beimplemented by any suitable system or electronic device. The steps ofFIG. 4 may be implemented entirely, or in part, by the electronic textmanager 108 residing on the e-book reader 102 shown in FIG. 1A. Inanother example, the steps of FIG. 4 may be implemented entirely, or inpart, by the electronic text manager 108 residing on the e-book server134 shown in FIG. 1B. The electronic text manager 108 may be implementedby software, hardware, firmware, or combinations thereof.

Referring to FIG. 4, the method includes determining text subgroupswithin an electronic text based on a similarity relationship of contentwithin each text subgroup (step 400). For example, the electronic textmanager 108 may select words, sentences, and/or paragraphs positioned inproximity to one another within the e-book 118 and that contain similarcontent to create a text cluster. Multiple text clusters may be definedwith the e-book 118. Information for associating the selected words,sentences, and/or paragraphs as a text cluster may be stored in the datastore 110. In one embodiment, subgroups may be created simply based onparagraph or chapter boundaries.

The method of FIG. 4 includes determining, for each text subgroup,another similarity relationship between content of the text subgroup andone or more other text subgroups (step 402). Continuing theaforementioned example of step 400, the electronic text manager 108 maydetermine a similarity score between the text cluster and other textclusters within the electronic text. It is noted that clusters maycontain one or more text subgroups. The electronic text manager 108 maydetermine a highest similarity score among the determined similarityscores.

The method of FIG. 4 includes linking, for each text subgroup, the textsubgroup to one or more other text subgroups based on the othersimilarity relationship (step 404). Continuing the aforementionedexample of steps 400 and 402, the electronic text manager 108 may linkthe text cluster to the text subgroup (or other text cluster) having thehighest similarity score. In another example, the electronic textmanager 108 may determine a similarity relationship between a textsubgroup and each other text subgroup positioned forward of the textsubgroup within the e-book 118. In this example, the electronic textmanager 108 may link the text subgroup to the forward-positioned textsubgroup having the highest similarity relationship. In another example,the electronic text manager 108 may apply a similar technique tobackward-positioned text subgroups for linking to thebackward-positioned text subgroup having the highest similarityrelationship. Further, for example, the electronic text manager 108 maystore a navigational aid in the metadata of the electronic text thatindicates association of the text subgroup to the linked-to textsubgroup(s).

The method of FIG. 4 includes presenting a navigational link (step 406).For example, the electronic text manager 108 may control the userinterface 112 to present a navigational link corresponding to adisplayed text subgroup that may be selected by the user for navigatingto another text subgroup linked to the displayed text subgroup.

The following is a detailed description of an embodiment of steps 400,402 and 404 of FIG. 4. In this example, the text of the e-book 118 maybe tokenized to generate tokens representing each word. Other suitabletokenization techniques may also be used to separate the text of e-book118 into sentences or groups of sentences. It is noted that tokenizationmay be a part of, a result of, or a pre-requisite for separating thetext content into subgroups (step 400). The following steps may then beperformed on a text segment at a time or the text of the e-book 118 as awhole. It is noted that the term “segment” is used here to denote eithera text subgroup or a text cluster.

Subsequently, natural language programming (NLP) techniques may beapplied to the words in text segments, such as part-of-speech (POS)tagging to identify each word as a noun, verb, adjective, adverb, and soon; named entity recognition (NER) to identify which words are namedentities, and whether they represent a person, place, thing,organization, and so on; parsing to generate semantic graphs and trees,such as dependency trees, from sentences; relationship extraction toidentify relationships between words and entities, such as “is a”, “hasa”, “in”, and so on; and the like.

Based on the output of methods like POS-tagging and NER, a vocabulary isgenerated for the text of the e-book 118, which is a collection of theunique words that occur in the text. The same words with different POStags (such as “desire” which may be a noun as well as a verb) may betreated as separate words in the vocabulary of the e-book 118. Wordsthat occur in a predetermined list of “stop-words” (that is, words thatmay occur frequently but provide little semantic value) may be filteredfrom the vocabulary so as to maintain only the more semanticallyrelevant words. Further, methods such as stemming and lemmatization maybe used to detect multiple forms of the same words. Ontology (such asfrom an ontological database, for example, Wikipedia) may also be usedto find interrelations between terms or related terms for a given word.A thesaurus database may be used to further disambiguate words or mapvarious forms or synonyms of words to canonical versions. For example,only one of many words that mean the same thing may be chosen torepresent all other meanings based on say, the form that is mostcommonly used, or the form that is alphabetically first or last, and soon. Concordances may also be used to identify related words and wordsenses given a current context (such as neighboring words) based on howoften words appear next to each other, how often words occur within acertain distance of each other; how often words are syntacticallylinked, and so on. These example techniques may aid in reducing the sizeof the vocabulary to semantically unique and more relevant words, whichmay increase precision as well as reduce the processing resourcesrequired.

Other suitable advanced techniques may also be used, such asco-reference resolution, which can identify the nouns, proper nouns ornamed entities to which a pronoun may refer, and anaphora resolution,which are co-references to previously mentioned entities. These methodsmay be performed to more accurately identify word occurrences in textsegments, and hence to generate a more accurate number of references toeach term, which may result in more meaningful term frequencies andinverse document frequencies. The resulting number of term occurrencesmay be used instead of, or along with, the number of occurrencesdetected without co-reference resolution. In one embodiment, the weightsassigned to resolved co-references may be lower than the weight assignedto the same term when referenced directly. This may be becauseco-reference resolution may produce erroneous results and thus skew theresults. Furthermore, co-reference resolution may be an expensivemethod, and current methods using simpler metrics such as termfrequency-inverse document frequency perform sufficiently well. Someother NLP methods used herein may even be designed to work withoutco-reference resolution, and hence their results may be affected by theuse of co-reference resolution. However, in some embodiments,co-reference resolution may be used to further fine tune the results andavoid incorrectly linking less related segments.

The vocabulary may be used to generate an index of terms that alsocontains the list of positions in the text of the e-book 118 that eachterm occurs at, as well as the subgroups in which the term occurs. Thisindex may be used to quickly look up the locations of and the subgroupscontaining each significant term.

Next, the term frequency-inverse document frequency (TF.IDF) scores aredetermined for each word in the vocabulary. In this embodiment, however,since the e-book 118 is the only document, the document frequency (DF)is actually represented by the text segment frequency, that is thenumber of text segments a term occurs in, instead of the number ofdocuments. Thus, in one embodiment, a segment is used in place of adocument as a unit of text, since all the relevant text may be containedwithin a single document (e-book 118), or a series of inter-relateddocuments. Thus, the inverse document frequency is actually the inversesegment frequency (ISF). Note that in addition, an actual IDF score mayalso be used along with an ISF, based on DF extracted from a corpus ofmultiple documents by standard means known in the art.

In one embodiment, a vector space model (VSM) is used to determinerelationships between segments. In a VSM, terms in a vocabulary arerepresented as weighted numbers in a vector, where the weights aredetermined based on term frequency, number of occurrences, TF.IDF, andso on. Term vectors may be generated for segments similar to how vectorsare created for entire documents in the art. A term vector is createdfor each segment by creating a vector of scores representing each termwith one element per term in the vocabulary. As mentioned before, lessrelevant terms may be filtered, using methods such as stop-words or bysorting and filtering the lowest weighted or least frequency words. Foreach term in the vocabulary for each segment, the count of occurrencesof that term in the segment is assigned to the element in the vectorcorresponding to that term in the vocabulary.

Each element in the vector may further be weighted based on variouscriteria. Weights may be assigned to words in vocabulary based on theirword type (POS tag, such as noun, verb, adverb), word frequency andfrequency distribution, named entity type (person, place, organization)if the word is determined to be a named entity and the like. In oneembodiment, named entities are weighted more heavily as they may bestrong indicators of narrative context. For example, named entities thatare persons may be assigned the highest weights, whereas named entitiesthat are places may be weighted next highest, and so on. Elements in thevector may be weighted by multiplying the previously assigned value(such as TF.IDF) with the assigned weight.

In an embodiment, the concept of “start-words”, as opposed to“stop-words”, is introduced and applied. Start-words are a predeterminedset of words that may be significant to the narrative or text,especially for different kinds of texts. Start-words may be weightedmore heavily for texts to which they are more relevant. For instance,for suspense novels, start-words may include “kill,” “stalk,” “mystery,”“murder,” “discover,” “investigate,” “surprise,” “shock,” and so on, orvarious forms thereof. For action novels, start-words may include“shoot,” “explosion,” “fight,” and the like. For technical texts,start-words may include technical terms specific to the field oftechnology to which the text is related. Note that specific start-wordsmay be used to identify, characterize and categorize specificsignificant sections of the text, such as events, major plotdevelopments, twists, other narrative structures, major results in amathematical proof, and so on. Start-words may even be specific toauthors, genres, and the like, or dynamically chosen based on readers'preferences. Start-words may be provided by human input, for instance byan author, publisher, editor, or reader. Start-words may also beautomatically generated using methods such as term extraction, keyworddetection, and so on, or a combination thereof. For example, start-wordsmay be automatically generated from a single document, a corpus ofrelated documents, a corpus of unrelated documents, or combinationsthereof. A combination of manual and automated methods may be used forgenerating start-words.

Next, for each segment, related segments are found by correlating wordscores (TF.IDF, word frequencies, weighted TF.IDF, and the like) in theterm vectors for the respective segments. In one embodiment, the cosinedistance metric is used. The cosine of each pair of vectors isdetermined to denote the semantic relatedness score, and the higher thecosine distance of vectors of two text segments, the more related thesegments may be. Applying this to all pairs of vectors generates asquare matrix of cosine distances, where the row and column of eachelement correspond to a respective text segment, and the element itselfrepresents the semantic or similarity relationship between thoserespective text segments. As the cosine distance is commutative, thismatrix is symmetric about the diagonal, and it is sufficient to onlycompute the cosine distance for each unique pair regardless of order. Itis noted that other methods and metrics may also be used to determinesemantic relatedness. Depending on whether the metrics used arecommutative, the matrix may or may not be symmetric. In an embodiment,each term in each segment is textually compared with each term in everyother segment to determine similarity or semantic relatedness. Inanother embodiment, each word in a segment may be indexed into ahash-table, and semantic relatedness between segments may be determinedby comparing the overlap of indexes or hashes of terms in thehash-table.

In an embodiment, only segments or vectors of segments whose positionsin the text of e-book 118 are at least a threshold distance from eachother may be considered for determining relatedness to each other. Thismay be done to avoid unnecessarily comparing and linking adjacentsegments that would have a much greater probability of having highsimilarity relationships simply by virtue of having a greaterprobability of containing discourse of the same sub-topics or sub-plots,and which may de-emphasize the similarity relationships to more distantyet relevant segments. Additionally, there may be limited value ingenerating semantic links to text segments that are adjacent or veryclose to each other, since the user may typically read those segments inthe same session and hence may not require re-reading, or may be able tonavigate to nearby sections much more quickly via direct navigation(page-flipping) than through semantic navigation.

In another embodiment, latent semantic analysis (LSA) may be used. Amatrix of word scores between columns corresponding to segments and rowscorresponding to terms may be generated. The dimensions of this matrixwould hence be determined by the number of segments and number of termsin the vocabulary. Singular value decomposition (SVD) may then beperformed on the matrix, and the resultant matrices may be used todetermine the most relevant terms by reducing the dimensions to containthe numerically largest elements. SVD may be useful in filtering noisyterms and returning the most relevant terms and relationships insegments.

In another embodiment, more complex methods such as parsing, informationextraction, relation extraction, natural language understanding, firstorder logic, discourse semantics, discourse representation, and so onmay also be used. For example, the POS-tagged and NER-processed tokensmay be “chunked” to separate them into sentences, and the sentences maybe provided to a parser that may generate a tree or graph structurecontaining each word and its syntactic or semantic relation to the otherwords in the sentences. This tree structure may be traversed to identifythings like attributes and properties of entities, and the like.Relation extraction may also be performed to identify relations betweenentities, for example, the sentence “John is an accountant inPhiladelphia” may be processed to determine that “John,” a person, and“accountant,” a noun or occupation, have an “is a” relationship, whereas“John” and “Philadelphia,” a place, have a “(located) in” relationship.

These relations may be further used to identify contexts in a segmentand find related segments. For instance, if a relation is identified ina sentence from a text segment (such as, “John left Philadelphia in1997”), related segments would include sentences where that samerelationship has been referenced (such as, in an earlier sentence, “Johnmoved to Philadelphia in 1990”). In addition, these relations may beused to identify latent or inferred references to entities associatedwith those relations wherever only one part of the relationship ismentioned. For the above example, in a text wherever the words “theaccountant” are mentioned, the system may infer that it refers to theperson “John.” To make finding related segments more efficient, theserelationships may be indexed and associated with the segments where therelationships are mentioned, so as to provide quick look-ups of therelated segments.

Parse trees for subsequent or adjacent sentences may be implicitlylinked into a graph with a chronological “followed by” relationship, orwith an index in a sequence or chronological timeline of the occurrencesdepicted in the sentences. Temporal references in the sentences mayaffect the placement of the tree in the sequence/timeline (for example,a sentence including a date may position the events in that sentence inthe timeline at that date, which may be different from the time of thecontext for the current sentence). Additional graph-based methods may beused to further identify strong semantic, similarity, causal or otherrelationships between non-adjacent segments (as an example, the LexRankmethod may be used for connecting significant sentences).

In another embodiment, a combination of vector space methods (such asVSM), SVD, statistical methods (such as term frequency-based) andadvanced methods (such as parsing and relation extraction-based methods)may be used to determine related segments.

After the related segments have been determined, the set of relatedsegments for each segment may be ranked and filtered to identify themost relevant related segments. The number of segments considered mostrelevant may be limited to maintain relevancy of suggested segments, andto avoid generating unnecessarily numerous related segments andnavigation links to them, which may result in undue extra processing andcrowding of the user interface with diminishing returns on relevance.Related segments may be ranked based on their relationship score asdetermined by the VSM, cosine distance or SVD methods.

Related segments that are directly adjacent to a current segment, orwithin a certain threshold of distance from the current segment (interms of length of words, sentences, passages, pages, etc.) may beexcluded on the premises that they are directly or easily viewable tothe user already; the user may have recently read them and so may notrequire re-reading; and they are more easily accessible by directnavigation (page-flipping) than by semantic navigation. As mentionedabove, this optimization may be used earlier in the process to reducethe number of vectors compared, thus reducing processing resourcesrequired. Further, some related segments may be ranked lower andfiltered out or ranked higher based on the time the user last read thatsegment. For example, if a significant amount of time has passed since auser has read a related text segment, there is a higher probability thatthe user has forgotten about it, and hence may wish to re-read it, thana text segment that the user has read very recently.

In an embodiment, some related segments may be ranked based onhistorical navigation behavior of other users, or users with similarprofile to the current user. For example, if there is a particularsegment that many users often flip back to re-read from one or moresubsequent segments, that particular segment is identified as aparticularly highly related segment and ranked higher.

The limit on the number of related segments may be a fixed number, afixed number in each direction (that is, before and after), apre-determined or dynamically selected fraction of the results, adynamic number based on the distribution of scores in a vector for agiven segment and so on. In an embodiment, the related segments for asegment may be sorted based on the similarity relationship scoresbetween them, and then all related segments following a sharp drop, say,greater than 10% difference, in the similarity relationship scorebetween adjacent sorted related segments may be filtered out.

Next, the method may find the most relevant terms relating each pair ofrelated segments. These terms may be useful in highlighting the words ineach segment and the related segment that provide the semantic orsimilarity relationships between the two segments. This may be doneusing the scores for the corresponding term in the vector correspondingto each segment. An example approach includes piecewise multiplying thescores corresponding to each term in each segment term vector togenerate an inter-segment term significance vector (ISTSV), whichdenotes the relevance of each term in the vocabulary for the two textsegments. Any term that does not occur in one or either segment may havea zero or very low score, and hence its score in the ISTSV will also bezero or very low. Conversely, a term that is prominent or frequent inboth segments will have a higher score in the ISTSV. Terms correspondingto the highest scores in the ISTSV are chosen as the words that are mostrelevant to the pair of related segments. The relevant terms may also betrimmed down, for example, using their ISTSV score, to keep only themost relevant ones. It is noted that the vocabulary may contain wordsthat have been stemmed, lemmatized or otherwise processed, so the set ofmost relevant terms may need to be mapped to the original wordsappearing in the segments. The POS type (noun, verb, adjective and thelike) and named entity type (name, place, thing and the like) of eachword may also be determined and associated with relevant terms.

Next, a record associating the two text segments is created, which maybe a data structure containing the relevancy score between the twosegments, the most relevant terms relating both segments, theircorresponding ISTSV scores, and the like. The records for the relatedsegments may be associated with the record or data structure for eachsegment. Related segments may be indexed by each relevant term toimprove look-up and fetching speed. The records may be stored in thedata store 110 of the e-book reader device 102.

Finally, using the records for related segments, navigation linksbetween each segment and the segments most related to it based onsemantic or similarity relationships may be generated.

In another embodiment, a heuristic direct reference-based linkingtechnique may be used to generate navigation links and to generate orrank additional related segments. For example, the electronic textmanager 108 may look for direct references to specific chapters,sections or passages and insert navigation links to the referenceschapters, sections or passages. As an example, every mention of “chapter2” in the text of e-book 118 may be implicitly made a navigation link tothe beginning of chapter 2 in the e-book 118. Similarly, every mentionof “section 5.1” in the text of e-book 118 may be implicitly made anavigation link to the beginning of section 5.1. The relevant chapterand sections may be identified by corresponding chapter or sectionheadings in the text, for example, using metadata or markup informationavailable along with the e-book 118. Furthermore, the electronic textmanager 108 may use the contextual information in the text surroundingthe direct chapter or section reference to more accurately specify theparticular relevant location or segment within the chapter or section,and generate the navigation link point so as to directly point to thatlocation. For example, when a sentence says “We saw in Chapter 5 howcaterpillars become butterflies”, the navigation link may point directlyto the specific text subgroups in chapter 5 that talk about caterpillarsbecoming butterflies, or text subgroups that contain the terms“caterpillar”, “become”, “butterfly”, or combinations and morphologicalforms thereof. It is noted that this may also apply to forwardreferences, for example, to sentences like “We will see in Chapter 5 howcaterpillars become butterflies.” Similarly, for example, in textbooksor technical texts, the system may identify direct references to tables,figures, charts, equations or formulae, and insert navigation links tothe corresponding tables, figures, etc., wherever they are mentioned.

In accordance with embodiments of the present disclosure, FIG. 5illustrates a flow chart of an exemplary method for graphicallyrepresenting similarity relationships between text subgroups within anelectronic text. The method of FIG. 5 is described with respect to theexample e-book reader 102 shown in FIGS. 1 and 2, although the methodmay be implemented by any suitable system or electronic device. Thesteps of FIG. 5 may be implemented entirely, or in part, by theelectronic text manager 108 residing on the e-book reader 102 shown inFIG. 1A. The electronic text manager 108 may be implemented by software,hardware, firmware, or combinations thereof.

Referring to FIG. 5, the method includes receiving search criteria forsearching an electronic text (step 500). For example, a user of thee-book reader 102 may interact with the user interface 112 for enteringsearch criteria such as, but not limited to, identification of a person,place, thing, the like, or combinations thereof. For example, the userinterface 112 may include a keyboard with which the user may enter thesearch criteria. As another example, the user may select words from thetext of the e-book 118 displayed on the user interface 112 to be used asthe search criteria, such as by highlighting with a mouse or by usingtouch gestures. The search criteria may be entered by the user forsearch of the e-book 118 for content related to the search criteria.

The method of FIG. 5 includes determining text subgroups within theelectronic text (step 502). For example, the electronic text manager 108may select words, sentences, and/or paragraphs positioned in proximityto one another within the e-book 118 and that contain similar content tocreate a text cluster. Multiple text clusters may be defined for thee-book 118. Information for associating the selected words, sentences,and/or paragraphs as a text cluster may be stored in the data store 110.In another example, text subgroups may be defined according to chapters,paragraphs, sentences, the like, and combinations thereof.

The method of FIG. 5 includes determining, for each text subgroup, asimilarity relationship between the search criteria and the textsubgroup (step 504). For example, the electronic text manager 108 maydetermine a similarity score between the search criteria and each of thetext clusters of the e-book 118. The electronic text manager 108 may usethe term vectors generated for each text cluster or subgroup todetermine a similarity score, for example, by representing the searchcriteria terms as a term vector and using VSM methods to determine themost relevant subgroups as well as the similarity relationships to eachsubgroup. In an embodiment, the index constructed using the vocabularymay be used to quickly identify the subgroups and locations of the termsin the search criteria. It is noted that along with the search criteria,the electronic text manager 108 may also include terms from the textcluster or subgroup at the user's current reading position, such thatthe context may be used to further narrow what the user may be searchingfor.

The method of FIG. 5 includes presenting, for each text subgroup, agraphic that represents the similarity relationship between the textsubgroup and the search criteria (step 506). For example, the electronictext manager 108 may control a display of the user interface 112 todisplay a graphic for indicating the similarity relationship between atext subgroup of the e-book 118 and user-entered search criteria. In anexample, a portion of the display may represent the text subgroups. Thetext subgroups may be defined by several displayed icons or otherindicia. The icons or other indicia may be colored differently toindicate a relevancy of the corresponding text subgroup to the searchcriteria. For example, the color red may indicate that the text subgroupis highly relevant to the search criteria, the color yellow may indicatethat the text subgroup has a medium relevancy to the search criteria,and the color blue may indicate that the text subgroup has low level ofrelevancy to the search criteria.

In an example, the display 200 of the e-book reader 102 shown in FIG. 2is controlled by the electronic text manager to display a graphic 204representing a similarity relationship of text clusters of the e-book.In this example, the phrase 202 is selected and the graphic 204indicates with colored portions 206, the text clusters relevant to thesearch criteria, i.e., the phrase 202. The graphic 204 may be a timelineor progress bar that is representative of one or more related portionsof the electronic text and that highlights the related portion(s). Theuser may interact with the user interface of the e-book reader 102 tointeract with the graphic 204 for navigating to one or more of therelated portions.

The method of FIG. 5 includes receiving user input for selecting one ofthe graphics (step 508). For example, the colored portions 206 of thegraphic 204 shown in FIG. 2 may be suitably selected by the user. Themethod of FIG. 5 includes controlling a user interface to presentcontent of the text subgroup associated with the selected graphic (step510). For example, the user may select one of the portions 206 shown inFIG. 2. In response to selection of the colored portion 206, theelectronic text manager 108 may control the display of the userinterface 112 to present content of the text cluster associated with theselected portion 206.

In accordance with embodiments of the present disclosure, an e-bookreader or other electronic device may define text subgroups according tochapters and/or paragraphs of an electronic text. An electronic textmanager, such as the electronic text manager 108 shown in FIG. 1A, maycontrol a display of one or more graphics associated with the chaptersand/or paragraphs. For example, one or more icons may be displayed thateach represent a chapter or paragraph of an e-book. Subsequently, a usermay suitably interact with one of the graphics to select the graphic(s).The electronic text manager may receive the user input for selecting thegraphic. In response to receipt of the user input, the electronic textmanager may present graphics representing relationships associated withuser-entered search criteria. For example, in response to receiving userinput selecting a graphic associated with a chapter of an e-book, theelectronic text manager may control a display to present graphicsrepresenting relationships between user-entered search criteria andparagraphs within the chapter. In another example, in response toreceiving user input selecting a graphic associated with a paragraph ofan e-book, the electronic text manager may control a display to presentgraphics representing relationships between user-entered search criteriaand sentences within the paragraph. Further, for example, the presentedgraphics may be an indicator of a similarity score between the searchcriteria and the corresponding portion (e.g., paragraph, sentence, andthe like) of the electronic text.

In accordance with embodiments of the present disclosure, links may begenerated based on user navigation behavior. The user navigationbehavior may be collected from one or more users of an electronic text.The user navigation behavior may be used alone or together with othertechniques disclosed herein for clustering or link generation. Moreparticularly, user navigation behavior may be aggregated and analyzed toidentify potentially relevant text subgroups or text clusters, and togenerate links between them.

In an embodiment, user navigation behavior may refer to the way and/ororder in which a user interacts with an electronic text, such as ane-book containing technical information. For example, user navigationbehavior may be detected by tracking one or more of: a current positionof a user within an electronic text (e.g., a page, chapter, passage,sentence, offset in a page, and the like of a user's position within anelectronic text); time spent by a user at a position within anelectronic text (e.g., the time spent at a position may be compared tothe average time that a user spends at a similarly sized portion of theelectronic text); a non-linear navigation of a user from a currentposition within an electronic text (e.g., “flipping” or “scrolling”between portions of an electronic text); determining or detecting whichnew portion of electronic text at which a user spends a predefinedamount; and determining or detecting which portion(s) of electronic textthat a user spends time at before returning to a current position withinthe electronic text. An electronic text manager, for example, may inferthat navigation and/or time spent by the user between various portionsin electronic text implies that there is a similarity or semanticrelationship between those portions. The electronic text manager may usethis information for identifying which portions should be clusteredtogether by analyzing which contiguous portions the user spent time at.The electronic text manager may use this information to generate linksbetween the portions or text subgroups. The links may be positioned inthe order that the user navigated the portions.

In accordance with embodiments of the present disclosure, FIG. 6illustrates a flow chart of an exemplary method of analyzing usernavigation of an electronic text for linking text subgroups within theelectronic text. The method of FIG. 6 is described with respect to theexample e-book reader 102 shown in FIGS. 1 and 2, although the methodmay be implemented by any suitable system or electronic device. Thesteps of FIG. 6 may be implemented entirely, or in part, by theelectronic text manager 108 residing on the e-book reader 102 shown inFIG. 1A. The electronic text manager 108 may be implemented by software,hardware, firmware, or combinations thereof.

Referring to FIG. 6, the method includes determining that a usernon-linearly navigates between text subgroups within electronic text(step 600). For example, the electronic text manager 108 of the e-bookreader 102 shown in FIG. 1A monitors a user's input for interacting withthe e-book 118. For example, the electronic text manager 108 maydetermine that the user has interacted with the e-book 118 bynon-linearly moving between chapters or other portions (e.g., textsubgroups) of the e-book 118. The electronic text manager 108 may alsodetermine the time spent at the different portions. This information andother information described herein may be used by the electronic textmanager 108 for determining that the user has non-linearly navigatedbetween text subgroups of the e-book 118.

In an example, user navigation behavior information may be aggregatedfrom multiple users and analyzed to detect navigation trends such as,but not limited to, non-linear navigation between text subgroups of anelectronic text. The information may be used to determine which textsubgroups that the users frequently, non-linearly navigate between.Based on this information, an electronic text manager may link the textsubgroups in accordance with the present disclosure.

In another example, aggregation of collective user navigation behaviorinformation may be performed by having multiple electronic devices, suchas the e-book readers 102 and 104 shown in FIG. 1A, track the navigationbehavior of their respective users. This information may be reported tothe e-book server 106. For example, the e-book readers 102 and 104 mayreport respective navigation behavior information about a particulare-book to the e-book server 106 via the network 116. In this example,the e-book server 106 may analyze the collected information fordetermining links between text subgroups in accordance with the presentdisclosure. The e-book server 106 may subsequently report the linkinformation to the e-book readers 102 and 104 for use in helping a userto navigate between text subgroups in accordance with the presentdisclosure. Further, for example, trend information across multipleelectronic devices may be used to identify relevant clusters andgenerate links in accordance with the present disclosure. Further, thisuser behavior information may be used to weight and prioritizeautomatically-generated links. The link information may be providedindividually to electronic devices as needed by users, or may becollectively downloaded by electronic devices as available.

The method of FIG. 6 includes linking the text subgroups in response todetermining that the user non-linearly navigates between the textsubgroups (step 602). For example, the electronic text manager 108 maylink the text subgroups together. Further, for example, the electronictext manager 108 may store a navigational aid in metadata of theelectronic text that indicates association of the text subgroups.

The method of FIG. 6 includes presenting a navigational link that linksthe text subgroups to one another (step 604). For example, theelectronic text manager 108 may control the user interface 112 topresent a navigational link corresponding to a displayed text subgroupthat may be selected by the user for navigating to another text subgrouplinked to the displayed text subgroup.

In accordance with embodiments of the present disclosure, a userinterface of an electronic device may be controlled to display textsubgroups related to a current position of a user within an electronictext. For example, FIG. 7 illustrates a flow chart of an exemplarymethod of controlling a user interface to display text subgroups thatare related to a current position of a user within an electronic text.The method of FIG. 7 is described with respect to the example e-bookreader 102 shown in FIGS. 1 and 2, although the method may beimplemented by any suitable system or electronic device. The steps ofFIG. 7 may be implemented entirely, or in part, by the electronic textmanager 108 residing on the e-book reader 102 shown in FIG. 1A. Theelectronic text manager 108 may be implemented by software, hardware,firmware, or combinations thereof.

Referring to FIG. 7, the method includes determining a current userposition within an electronic text (step 700). For example, theelectronic text manager 108 of the e-book reader 102 shown in FIG. 1Amay determine a page number, chapter number, passage identifier,sentence identifier, offset in a page, and the like of a user's positionwithin an electronic text. The current user position may correspond tothe page, chapter, and the like that is currently being displayed to theuser. For example, FIG. 8 illustrates a front view of an e-book reader102 displaying a portion of an electronic text within a display area800. The text within the display area 800 shown in FIG. 8 corresponds tothe current user position within the electronic text.

The method of FIG. 7 includes determining a current text subgroupcorresponding to the current user position (step 702). Continuing theexample of step 700, the electronic text manager 108 shown in FIG. 1Amay determine a current text subgroup corresponding to the current userposition within the electronic text. For example, thecurrently-displayed text within the display area 800 shown in FIG. 8 maycorrespond to a text subgroup defined in accordance with the presentdisclosure. The currently-displayed text may include the entirety or aportion of the content of the text subgroup. The electronic text manager108 may determine that the currently-displayed text within the displayarea 800 corresponds to a previously-defined text subgroup, which may bereferred to as a current text subgroup since all or a portion of it iscurrently being displayed.

The method of FIG. 7 includes displaying in a first display area, aportion of the electronic text corresponding to the current textsubgroup (step 704). For example, the electronic text manager 108 maycontrol the display 200 shown in FIG. 8 to display in the display area800, the text corresponding to the current text subgroup.

The method of FIG. 7 includes displaying in a second display area, oneor more related text subgroups positioned before the current textsubgroup (step 706). Continuing the aforementioned examples, theelectronic text manager 108 may control the display 200 shown in FIG. 8to display in a display area 802, content of one or more text subgroupspositioned before the current text subgroup. Within the display area802, the display 800 may display text of a text subgroup that ispositioned before the current text subgroup and that has a similarityrelationship to the current text subgroup in accordance with the presentdisclosure. The text displayed within the display area 802 may includethe entirety or a portion of the content of the corresponding textsubgroup.

The method of FIG. 7 includes displaying in a third display area, one ormore related text subgroups positioned after the current text subgroup(step 708). Continuing the aforementioned examples, the electronic textmanager 108 may control the display 200 shown in FIG. 8 to display in adisplay area 804, content of one or more text subgroups positioned afterthe current text subgroup. Within the display area 804, the display 800may display text of a text subgroup that is positioned after the currenttext subgroup and that has a similarity relationship to the current textsubgroup in accordance with the present disclosure. The text displayedwithin the display area 804 may include the entirety or a portion of thecontent of the corresponding text subgroup. It is noted that step 708,along with the display area 804 and the text contained therein, may beoptional. For example, when reading a novel, the user may not wish to beshown forthcoming text that he or she has not yet read, as that may giveaway plot elements and negatively affect the reading experience.However, the display area 804 may be displayed if the corresponding textsubgroup positioned after the currently displayed text subgroup hasalready been read by the user, for instance, when the user hastemporarily navigated to a text subgroup positioned behind the currenttext subgroup.

In an embodiment, the electronic text manager 108 may sort the relatedtext subgroups displayed in the display areas 802 and 804 by asimilarity score between each corresponding text subgroup and thecurrent text subgroup. For example, the electronic text manager 108 maydetermine a similarity score between the current text subgroup and eachtext subgroup positioned before and/or after the current text subgroup.The electronic text manager 108 may sort or rank the text subgroupsbased on the similarity score. For example, the text subgroupspositioned before the current text subgroup may be sorted from highestto lowest similarity score. Further, for example, the text subgroupspositioned after the current text subgroup may be sorted from highest tolowest similarity score. In an example, all or a portion of the contentof one or more text subgroups having the highest similarity score may bedisplayed in the display area 802 or 804. Further, for example, for eachdisplayed text subgroup, the electronic text manager 108 may control thedisplay 800 to display a graphic as an indicator of similarity in anarea adjacent to the display area for each corresponding text subgroup.In an example, the graphic may be a value of the similarity score or acolor as disclosed herein for indicating the similarity. Text subgroupsmay be ranked or sorted based on a number of metrics including, but notlimited to, a level of semantic relation, occurrence of similarkeywords, presence of similar entities, the like, and combinationsthereof. Display area 806 may be selectable by suitable user input, anduseable for manipulating, controlling, and/or refining user navigationoptions.

In an embodiment, the electronic text manager 108 may display anavigation link to the corresponding text subgroup instead of a portionor all of the content of that subgroup in display areas 802 and 804. Inanother embodiment, the display areas 802 and 804 may be displayed alongwith the corresponding text, but additionally, in part or whole, may actas a navigation link themselves. The user may interact with the displayareas 802 and 804 through, for example, a touchscreen display 200, tonavigate directly to the position of the corresponding text subgroup inthe e-book 118. The display area 802 may also display other informationabout the related text subgroups, such as graphical indications ornumeric representations of the relevancy score, the most relevant termscommon to the current text subgroup in display area 800 and the relatedsubgroup, the inter-segment term significance vector scores of thecommon relevant terms, the relative or absolute location of the relatedtext subgroup, and so on.

In an embodiment, a display area 806 may be displayed on the display200. This area may provide controls with which a user may refine ormanipulate the selection of and navigation to the related subgroups. Forinstance, as shown in FIG. 8, the display area 806 may include userinterface (UI) controls to allow the user to manipulate the selection ofrelated segments by adjusting the significance assigned to various wordtypes in selecting related subgroups. In this example, the controls aredisplayed as a “tag cloud,” allowing the user to adjust significance forpersons, places and things. Hence if a user seeks related subgroupsbased on the characters referenced in the current text subgroup, he mayassign more significance to the “person” tag. Adjusting the tag cloudsmay adjust different weights to the common relevant terms associatedwith the record of each pair of subgroups and the related subgroups,which may also be associated with their POS word types as well as namedentity types. These adjusted weights may then be used to determineupdated semantic relationship scores between the subgroups, and adjustthe ranking, filtering and selection of presented related subgroups.

It is noted that to reduce processing resources required, such as CPUand memory, only a subset of the text subgroups nearest to the currenttext subgroup and their corresponding related subgroup records may beaccessed and loaded in memory, either in advance or on-demand.

The displayed portion of texts in display area 800 may be enabled withpossible navigation-related actions, such as by embedding actionablehyperlinks in relevant common terms, or presenting UI elements such asbuttons, or associating touch gestures on the displayed portion of atext portion with navigation-related actions (for touchscreen devices).These elements may be invisible or non-highlighted until a user performsan action on the displayed text segment, for example by performing amouse-over it, or touching it. When such a user action is received, theelectronic text manager 108 may then present the navigation optionsavailable for the text subgroup corresponding to the text segment. In anembodiment, the electronic text manager 108 may highlight the currentsubgroup contained within the display area 800, for instance by changingthe color of the text, or the background color of the text segment, toindicate to the user the current text segment with respect to whichcorresponding related segments may be found. This may serve to providethe user visual feedback as to what the electronic text manager 108considers the current reading context. In an embodiment, a user may beable to manipulate the boundaries of the selected text subgroup bycontracting or expanding it, which may also affect the scope of relatedsubgroups. The user may also be able to select additional sections of,or whole other, adjacent subgroups to expand the scope of relatedsubgroups. In this case, the number of candidate related segments isautomatically greater. Hence, the most relevant of these may be selectedeither on-demand or in advance, by treating the user-selected segment asa single text subgroup and finding related subgroups using the methodsabove.

The electronic text manager 108 may then determine the availablenavigation options. As described previously, the electronic text manager108 retrieves, ranks and filters the related subgroups based on thesubgroup of text the user is currently located at, or has currentlyperformed an action (such as a mouse, keyboard, gesture event, and thelike) on. If the user specifically has selected or highlighted somewords in the current text subgroup, the electronic text manager 108 usesthose to dynamically filter and rank the related segments. Relatedsegments may be indexed by each relevant term to improve look-up andfetching speed. Alternately, the electronic text manager 108 may alsoattempt to guess what the user wants and present (or automaticallyexecute) only the most probable action, for instance, based on actionsby other users previously on the same segment of the text, or similarsegments of texts.

In an embodiment, the electronic text manager 108 may only displaynavigation options links to related segments that occur before thecurrent segment. This is because users typically may want to re-readonly previously read sections, and because reading ahead may negativelyaffect the reading experience, for example, via spoilers. Thus, even iflinks to subsequent subgroups are available, it may be preferable to notpresent them because with accidental navigation the user may get aheadof himself and potentially spoil the reading experience. In anembodiment, forward navigation options may not be initially presented,but may be presented if the user explicitly requests them, for exampleby right-clicking on some link, or using another gesture, and the like.Forward navigation options may also be automatically presented if thenavigation is to segments the current user has already read at leastonce. If the user is not the same, or there is doubt about useridentity, forward navigation options may be preferably hidden.

The electronic text manager 108 may then present the availablenavigation options. The electronic text manager 108 may arrange links ina separate navigation area, such as 802 and 804, based on the score/rankand distance from the current text subgroup. It is noted that thisconstitutes an “in-place” display model, where the related subgroupoptions may be presented in a fixed portion of the display, and thenavigation may be contained within only that portion of the display,such that the current text subgroup is always visible to the user. Forexample, in FIG. 8, all navigation may be contained to the portions 802or 804 or both. In another embodiment, as mentioned above, the relatedsegment content may be displayed as an overlay or pop-over, preferableplaced unobtrusively. However, in an alternate embodiment, theelectronic text manager 108 may provide a navigation-based model, wherethe user actually navigates to the location of the related subgroup inthe document. The following three methods may be used in conjunctionwith either an in-place display model or a navigation-based model.

In an embodiment, the navigation options may be presented as discrete UIelements, such as hyperlinks or buttons with descriptive textidentifying the related subgroups and corresponding metadata, includinginformation such as corresponding page number, relevant keywords,semantic relationship scores, and the like.

In another embodiment, the links may be embedded within the text of thecurrent subgroup, for example, by converting one or more relevant commonterms in the text into actionable hyperlinks The hyperlinked words mayeither point to the start of the most relevant segment; point directlyto an occurrence of the relevant words in the text of the most relevantsegment; or on being clicked in, may display a list of related segments,potentially filtered and ranked by the word that has been clicked.

In yet another embodiment, the options to navigate to related subgroupsmay be presented along with the corresponding text in separate displayareas, such as 802 and 804 in FIG. 8. The text from the correspondingcandidate related subgroups may be contracted or shortened when beingpresented in order to conserve display space, especially if there areseveral candidate subgroups. In one embodiment, the text content of therelated subgroup may be contracted simply by truncating it after a fixedword or character length, preferably at a word boundary, and appendingellipsis (“. . .”). In another embodiment, advanced methods such assummarization may be used to generate a summary for related subgroups.Query-biased summarization methods may be used by using the relevantterms common to the current and related subgroups, and/or user-selectedtext, as the query terms to bias the summarization with, such that themost relevant sentences are displayed. The text, if contracted, may beexpanded if the user so requests, such as by clicking or gesturing onit. The electronic text manager 108 may highlight relevant terms commonto the current and/or related subgroups to visually indicate to the userthe words that provide the basis of the semantic relationship betweenthe two text segments.

Along with links to related segments, the system may also present acurrent relevancy score; a list of most relevant or common terms; agraphical or other indication of the relative or absolute locations ofthe related segments; and the like.

The electronic text manager 108 may then detect user actions on thepresented navigation options. The electronic text manager 108 may detectactions specific to the UI method, for instance, navigation gestures ontouchscreen devices or mouse events on browsers. On receiving a useraction on a link, the electronic text manager 108 may then control theUI 200 to navigate to the selected related subgroup. As describedpreviously, using a link may navigate either to the start of the relatedsegment; or the most relevant part of the related segment, that is, thesection where most of the relevant words occur. Alternately, instead ofnavigating to the related subgroup, a portion of the display area suchas 802 may be updated to display the text of the related subgroup. Onnavigation to a related segment, the electronic text manager 108 mayhighlight the exact related subgroup, such as by changing color of textor background color of the section and so on, to precisely identify tothe user where the most relevant related text may be. The display may bepresented such that the related subgroup is centered on the displayscreen, or alternately at the top, to instantly capture the user'sattention. The electronic text manager 108 may highlight the relevantcommon terms in the related subgroup only after the user navigates toit.

As a user navigates through the related segments, the electronic textmanager 108 may maintain a linked list of subgroups the user hasnavigated through as a sequence of “breadcrumbs.” The breadcrumbssequence helps the electronic text manager 108 accept user navigationcommands and navigate correctly by traversing back and forth along thelist. It is noted that the breadcrumbs list may be a graph, specificallya tree, for complex navigation sequences that traverse the same relatedsegment multiple times. It is noted that breadcrumbs may be a purelyinternal management data structure, as well as a UI element depictingthe user's navigation history, such as seen on many Internet websites.

The electronic text manager 108 may also provide a quick “jump back”navigation option, which may be an easily accessible link, button orgesture to navigate back to the previous segment in the trail ofbreadcrumbs, or directly to the start of the breadcrumb trail, that is,the current text subgroup where the user ceased linear progress andstarted navigating non-linearly. When the user jumps back or otherwiseresumes linear progress, the breadcrumb records may be deleted frommemory. However, before deletion, the navigation details in thebreadcrumbs may be uploaded to the server 106 as an instance ofnon-linear navigation for analysis and aggregation, as described in moredetail subsequently.

In accordance with embodiments of the present disclosure, semanticnavigation of an electronic text may be enabled by traversing a semanticgraph or cause/effect graph of relations between entities such as, butnot limited to, characters, places, objects, various plot elements, andthe like. A semantic graph may be generated statically (e.g., by humaninput) or dynamically (e.g., by semantic or statistical analysis). Asemantic graph may be generated, for example, manually such as by humaninput in the form of annotations, markup, and the like provided by anauthor, editor, or editorial staff. In another example, a semantic graphmay be generated collaboratively such as by a community of readers. Inanother example, a semantic graph may be generated automatically by asuitable technique such as, but not limited to, semantic analysis;natural language processing; techniques such as tokenizing,part-of-speech tagging, named entity recognition, stemming,lemmatization, parsing, relation extraction, latent semantic analysis,vector space models, and singular value decomposition; identification ofcausal relationships between portions of an electronic text (e.g., atext seed and a text subgroup); semantic similarity based on ontology; asemantic index for comparing semantic similarities; and a statisticsimilarity; and passive observation of users reading an electronic text(e.g., noticing when a user uncharacteristically flips back from acertain position, and noting from where and to where he or she flips). Asemantic relation between text subgroups may be determined based onthese examples and others disclosed herein.

In an embodiment, navigation links may operate to enable “in-place”display of the related content. The user may click, touch, or otherwiseselect an available navigation link, and instead of the UI changing theuser's position in the text to that of the related text subgroup thatthe navigation link points to, the UI may display the related content,for example, in a pop-up or an overlay, or in a second area of thedisplay as shown in FIG. 8. Particularly, if the related subgroupcontains figures or diagrams, the navigation may involve simplydisplaying the relevant figure or diagram along with the currentlydisplayed text subgroup, for instance, as a non-intrusive pop-up oroverlay. This way, when a text subgroup discusses a specific figure, thereader may not have to navigate back and forth from the figure whilereading the associated text. This behavior may switch dynamically basedon the distance of the figure from the corresponding text, for example,if the figure is on the same page or within a threshold distance, thismethod may not be used. As an example, in many patent documents thefigures are near the beginning of the document, but the relevantdescriptive text may be very far into the body of the document.Navigating back and forth may become annoying quickly, especially if thefigure has many different elements in complex configurations thatrequire constant flipping between the text describing those elements andthe diagram. In an embodiment, the electronic text manager 108 mayidentify the referenced figure and overlay it at a non-obtrusiveposition, and may focus or zoom in on an element the user has selectedor is currently reading about. Alternatively, the electronic textmanager 108 may navigate to the figure and focus or zoom in on anelement the user has selected or is currently reading about. Note thatthe same may be applied to text segments.

In accordance with embodiments of the present disclosure, metadata of anelectronic text or other data associated with an electronic text mayinclude various information defining text subgroups, text clusters,and/or navigation links as disclosed herein. This information may bedefined or generated collaboratively by readers of the electronic text,authors of the electronic text, editors of the electronic text, and/orothers. The information may be generated and shared among these users.For example, referring to FIG. 1A, e-book readers 102 and 104 maycommunicate with the e-book server 106 via the network 116 forretrieving e-books along with such information. In addition, e-bookreaders 102 and 104 may generate such information in accordance with thepresent disclosure and communicate the information to the e-book server106 via the network 116. This information may be stored by the e-bookserver 106 in a data store 120, which may store one or more differente-books 122 and associated metadata 124.

The e-book server 106 may include a processor 126 configured toimplement the functions disclosed herein. For example, the processor 126may be configured for collecting information defining text subgroups,text clusters, and/or navigation links as disclosed herein. Further, thee-book server 126 may include a network interface 128 configured tocommunicate with the network 116 or another communications network forexchanging information and data with the e-book readers 102 and 104,servers, or any other electronic devices.

The data store 120 of the e-book server 106 may store user accountinformation 130 including information about the users of e-book readers102 and 104 and other electronic devices. In an example, a user of thee-book reader 102 may register for an account with the e-book server106. The user may enter his or her information by interaction with theuser interface 112, and the e-book reader 102 may communicate thisinformation to the e-book server 106 via the network interface 114. Theinformation may be stored in the user accounts 130. Further, forexample, the user may interact with the user interface 112 to requestthe download of an e-book from the e-book server 106 via the network116. The e-book may be downloaded to the e-book reader 102 via thenetwork 116 upon completion of a purchase transaction. In addition tothe e-book, the e-book reader 102 may receive metadata associated withthe e-book. An unregistered user may receive default metadata for thee-book. A registered user may make changes to the metadata that arepersisted across viewing sessions, and may contribute edits to themetadata stored in the e-book server 106. The e-book server 106 mayreceive from e-book readers information for use in determining textsubgroups, text clusters, and/or navigation links in accordance with theembodiments disclosed herein.

In accordance with embodiments of the present disclosure, FIG. 9illustrates a flow chart of an exemplary method of clustering textwithin an electronic text based on a similarity relationship betweenadjacent sentences. The method of FIG. 9 may be implemented by thee-book server 106 or one of the e-book readers 102 and 104. Referring toFIG. 9, the method includes obtaining text to analyze (step 900). Forexample, the e-book server 106 may obtain text of an e-book.

The method of FIG. 9 includes analyzing the text and determiningweighting for each unique word (step 902). For example, the server 106analyzes the text for determining the word frequency for each wordoccurring in the e-book (i.e., determining “term frequency”). For eachword occurring in the text, the server 106 determines word weighting bymultiplying the term frequency by the inverse document frequency to givea TF.IDF measure. In an embodiment, other variations of TF.IDF may beused, such as one determined by multiplying by the term frequency by thelogarithm of the inverse document frequency. The inverse documentfrequency may be determined by counting the number of times a wordoccurs in a large number of documents. These frequencies may bedetermined separately for different specific domains or genres (e.g.,suspense novels may have very different significant terms than romancenovels, or technical documents on audio processing may have verydifferent significant terms than books on archaeology). Either manualinput in the form of tags and metadata, or suitable automatedtechniques, may be used to detect the domain a document's contentsbelong to, and to determine the appropriate significant terms for it.Example common words include, but are not limited to, the words the, of,to, in, a, is, that, be, it, by, are, for, was, as, he, with, on, his,at, which, but, from, has, this, will, one, have, not, were, or, all,their, an, I, there, been, many, more, so, when, had, may, today, who,would, time, we, about, after, dollars, if, my, other, some, them,being, its, no, only, over, very, you, into, most, than, they, day,even, made, out, first, great, must, these, can, days, every, found,general, her, here, last, new, now, people, public, said, since, still,such, through, under, up, war, well, where, while, years, before,between, country, debts, good, him, interest, large, like, make, our,take, upon, and what. Such common words, also known in NLP as “stopwords”, may be given very low significance when attempting to identifyif two word fragments are related. Words corresponding to persons,places, or things occurring in the text of an e-book may be givenadditional weighting. For example, the names of the characters in astory may be given significance when trying to identify whether two wordfragments are related. As described previously, such words may beidentified using methods such as named entity recognition, along withheuristic methods based on the text, such as by assuming words that areconsistently capitalized throughout the text to be named entities. Inaddition, other methods previously described may also be used, such astokenizing, POS-tagging, stemming, co-reference resolution, and thelike.

The method of FIG. 9 includes obtaining clustering parameters (step904). For example, the server 106 may obtain clustering parameters thatinclude variables such as, but not limited to, minimum cluster size,names of characters, places, and things, penalty weights for clusteringacross programs and chapters, and the like.

The method of FIG. 9 includes randomly selecting sentences to act astext seeds (or clustering seeds) (step 906). For example, the server 106may determine initial text seeds by randomly selecting sentences fromthe text of the e-book. In another embodiment, a semantic relevancescore may be assigned to sentences, and the seed sentence may beselected based on this score. In an embodiment, a sentence may beselected as a text seed based on its position within the text of thee-book. It is noted that the text clusters generated may be affected bythe selection of the text seed.

The method of FIG. 9 includes obtaining a text subgroup (step 908). Forexample, a text seed may be obtained to function as an initial textsubgroup. Subsequently, the method of FIG. 9 includes determining asimilarity score between the text subgroup and a sentence immediatelybefore and immediately after the text subgroup (step 910). For example,the server 106 may determine a similarity score or other semanticrelationship between the text subgroup and a sentence immediately beforeand immediately after the text subgroup. The method of FIG. 9 includespenalizing the similarity score if the text subgroup has grown toolarge, links spanning paragraphs, or links spanning chapters (step 912).The method of FIG. 9 also includes determining whether the text includesmore subgroups (step 914). For example, the server 106 may determinewhether there is another text subgroup to analyze. If there is anothertext subgroup, the method may proceed to step 908 for application ofsteps 910 and 912 to the other text subgroup. These steps may berepeated until there are no additional text subgroups for analysis.

The method of FIG. 9 includes merging the text subgroups one-by-one witha previous or next sentence that has the highest similarity score toform a modified text subgroup (step 916). For example, the server 106may determine, for a given text subgroup, which of the sentencesadjacent to it has the highest similarity score. The sentence having thehighest similarity score is merged to the text subgroup to form themodified text cluster. In an embodiment, if both sentences have asimilarity score above a threshold level, both sentences may be mergedwith the text cluster to form a modified text subgroup. Conversely, ifone or both of the sentences have a similarity score below a thresholdlevel, neither sentence may be merged into the text subgroup.

In an example, FIG. 10 illustrates a diagram depicting a clusteringprocess for an electronic text in accordance with the presentdisclosure. Referring to FIG. 10, the content of the electronic text isrepresented as beginning at an end 1000 and ending at an opposing end1002. Text subgroups are shown as being divided by vertical lines 1004.In this example, a similarity score is determined between text subgroup1006 and the text subgroup 1008 positioned before it. Also, a similarityscore is determined between the text subgroup 1006 and the text subgroup1010 positioned after it. The text subgroup 1006 is combined with thetext subgroup 1008 or 1010 having the highest similarity score to form amodified text cluster.

The method of FIG. 9 includes determining whether all sentences havebeen assigned to at least one cluster (step 918). In response todetermining that all sentences have not been assigned to a cluster, themethod proceeds to step 908 until all sentences have been merged with atext cluster. In response to determining that all sentences have beenassigned to a cluster, the method may stop (step 920). If there areun-assigned sentences remaining, the method may repeat. In oneembodiment, the next seed text for subsequent iterations may be selectedfrom the remaining unassigned sentences by selecting: an adjacentunassigned sentence; an unassigned sentence with the highest semanticrelevance score; an unassigned sentence that is centrally located withina contiguous set of unassigned sentences; an unassigned sentence that iswithin a threshold range of distance from the one or more previouslyselected text seeds; an unassigned sentence that is within a thresholdrange of semantic or similarity difference from the one or morepreviously selected text seeds; or combinations thereof. It is notedthat sentences may not always be exclusive to a single text cluster, andhence some sentences may be common to two adjacent text clusters.Further, as mentioned previously, the method of FIG. 9 may be appliedrecursively to text clusters to generate text sub-clusters so as toenable, for example, hierarchical organization and navigation.

Subsequent to associating all portions of the electronic text with atext cluster, forward and backward links may be assigned for each textcluster. In accordance with embodiments of the present disclosure, FIG.11 illustrates a flow chart of an exemplary method of assigning forwardand backward links for each text cluster of an electronic text. Themethod of FIG. 11 may be implemented by the e-book server 106 or one ofthe e-book readers 102 and 104. Referring to FIG. 11, the methodincludes obtaining a text cluster (step 1100). For example, the e-bookserver 106 may obtain one of the text clusters generated in the methodof FIG. 9.

The method of FIG. 11 includes determining a similarity measure betweenthe current text cluster and every other text cluster (step 1102). Asimilarity measure may be determined using any of the methods describedpreviously, such as tokenizing, POS-tagging, named entity recognition,stemming, weighting, vector space modeling, latent semantic analysis,parsing, relation extraction, and the like. These similarity measuresare associated with the corresponding links between the pair of textclusters. Subsequently, the links are sorted according to direction andsimilarity measure (step 1104). For example, for each text cluster,forward links are sorted according to the similarity measure or scoreand direction. In addition for each text cluster, for example, backwardlinks are sorted according to the similarity measure or score anddirection. Further, the sorted links and their respective similaritymeasures are stored (step 1106). As described previously, the mostrelevant terms common to the related text clusters, along theircorresponding POS types, named entity types and ISTSV scores, may alsobe stored along with the links.

FIG. 12 illustrates the diagram shown in FIG. 10 in which a process forlinking the text cluster 1006 is implemented in accordance withembodiments of the present disclosure. Referring to FIG. 12, the textsubgroup 1006, which is defined as a text cluster in this example, iscompared to all other text clusters to determine the forward andbackward links with the highest similarity, or lowest distance. In anembodiment, text clusters that are adjacent or within a thresholddistance of each other are not compared, to avoid generating links tonearby text clusters for reasons described previously.

The method of FIG. 11 includes determining whether there are more textclusters (step 1108). If there are more text clusters, the methodcontinues to step 1100 to obtain another text cluster. Thus, the steps1102, 1104, and 1106 are implemented for all text clusters in theelectronic text. If there are no more text clusters, the method stops(step 1110). In an example, this link information for each text subgroupmay be stored as metadata in the data store 120.

FIG. 13 illustrates the diagram shown in FIGS. 10 and 12 in which alllinks for all text clusters have been completed in accordance withembodiments of the present disclosure. Referring to FIG. 13, the arrows1300 indicate the forward link from a text cluster to the forward textcluster having the highest similarity score. The arrows 1302 indicatethe backward link from a text cluster to the backward text clusterhaving the highest similarity score. It is noted that a graphicrepresentation of relations between text clusters similar to that inFIG. 13 may be generated dynamically using computer graphics methods andpresented to a user to illustrate the inter-relationships betweenvarious segments of the text.

In accordance with embodiments of the present disclosure, FIG. 14illustrates a diagram depicting a heat map of an e-book. The diagram maybe displayed by a display of an e-book reader or another suitableelectronic device. Referring to FIG. 14, the diagram depicts chapters1400 of the e-book and search criteria 1402 for selection by a user. Theuser may interact with a user interface of the e-book reader forselecting boxes 1404 corresponding to persons, boxes 1406 correspondingto places, and boxes 1408 corresponding to things. The candidate searchcriteria presented in boxes 1404, 1406 and 1408 may be determined eitherthrough manual input, such as by an author, editor, publisher or user,or may be automatically generated using methods such as named entityrecognition. The displayed heat map can changed based on the selectionof the boxes 1404, 1406, and 1408. It is noted that the method mayautomatically filter candidate search criteria whose selection may havelimited or less meaningful effects on the heat map. For example, themain protagonist in a novel, who may be referenced in every chapter, maynot be a useful search criterion, since selecting that criterion mayuniformly affect the entire heat map displayed and may not aid a user inisolating relevant chapters. The search criteria corresponding to theselected boxes are used for determining a similarity with each chapter1400. For example, a similarity score can be generated for each chapter.Further, each chapter can be colored based on its respective similarityscore. In this way, a user can view the colors of the chapters 1400 todetermine a relevancy of the chapter to the selected search criteria. Inaddition, the user may interact with the displayed graph to select achapter. In response to selection of the chapter, the e-book reader maydisplay the selected chapter's content.

In accordance with embodiments of the present disclosure, a hierarchicalsearch or navigation method may be implemented to allow a user tovisually identify sections of relevant text based on one or more searchcriteria. A user may specify search criteria, for example by keyboardinput, selecting sections of displayed text, or selecting from apre-determined list of search criteria. In response to specifying thesearch criteria, a visual indication of relevant chapters, paragraphs,and sentences may be presented as shown in diagrams 1500, 1502, and 1504of FIG. 15, which illustrates diagrams of heat maps for hierarchicalnavigation of an e-book. The portions of each of diagrams 1500, 1502,and 1504 may be colored differently for visually indicating a relevancyof that particular portion of the e-book. In this example, the user mayselect a chapter 1506 to further pinpoint relevant paragraphs 1502 asshown in the diagram. Further, the user may select a paragraph 1508 tofurther pinpoint relevant sentences 1504 as shown in the diagram. In anembodiment, this hierarchical navigation or search structure may bedetermined by recursive application of the clustering method. In anotherembodiment, the hierarchical navigation or search structure may bedetermined by recursively determining semantic relation of the searchcriteria to smaller text subgroups contained within a selected textcluster.

In accordance with embodiments of the present disclosure, a user mayinteract with a user interface with an electronic device as disclosedherein for utilizing navigation links to access content in an electronictext that is related to currently-displayed content. For example, a usermay interact with the display 200 shown in FIG. 2 to select the phrase202 for displaying content having a semantic relationship to the phrase202. In an example, the phrase 202 and its surrounding area may appearsimilar to other displayed text unless the phrase 202 is “clicked upon”or “moused over.” Thus, in this example, the navigational linkassociated with the phrase 202 remains invisible until interacted withby user input. The linked-to portion of the electronic text may be“zoomed in” on or otherwise highlighted for distinguishing it from otherportions of the electronic text.

In accordance with an embodiment of the present disclosure, a user maynavigate through text related to a navigation link by making backwardand forward flipping motions on a display. For example, the user maytouch the display 200 shown in FIG. 2 to make flipping motions over thephrase 202 to navigate back and forth through text related to the phrase202. Alternate touch gestures for navigation may include, for example, acounter-clockwise circle or semi-circle for backward navigation, orjumping to backward links, either to the most relevant segment or theclosest relevant segment before the current displayed segment; aclockwise circle or semi-circle for forward navigation, or jumping toforward links, either to the most relevant segment or the closestrelevant segment after the current displayed segment; and so on. Thesegestures may be reversed, or more intuitive ones chosen, for Japanese,Chinese, Arabic text and the like. The device may also provide, or theuser may also configure, specific gestures for specific navigations. Inan example, the user may return to the original text by appropriateinteraction with the display 200 such as by, for example, a singleclick, tap, or touch screen gesture on the display 200.

In an example use of an electronic device disclosed herein, a user maybe reading an e-book residing on an e-book reader such as the e-bookreader 102 shown in FIG. 1A. During reading, the user may becomeconfused as to the subtleties of the story. The user may select apassage explaining, for example, the inter-contradictory rules that makeup the story. At each sentence, the user may interact with the userinterface 112 to select one or more words. The electronic text manager108 may receive the selected word(s) and, in response to receipts of theword(s), it may control the user interface 112 to display a timeline ofpassages deemed to be related to the selected word(s). As the userselects additional words and/or phrases, the timeline may be updated toshow new related passages. Further, for example, the user may interactwith the display of the e-book reader 102 for indicating that he or shewants a “semantic replay” related to the selected word(s). In response,the e-book reader 102 may, for each selected word or phrase, navigate toa previous passage that illustrates how that rule affects anothercharacter.

In another example use of an electronic device disclosed herein, a usermay be reading an e-book residing on an e-book reader such as the e-bookreader 102 shown in FIG. 1A. In this example, the user may be interestedin a character mentioned early in the story. Near the end of the story,the character is mentioned again. By this time, the user may haveforgotten a detail about the character. As a result, the user mayinteract with a portion of the display including text about thecharacter (e.g., “tapping” on the display at a pronoun referring to thecharacter). In response to receipt of the user input, the electronictext manager 108 may control the display to navigate to the introductionof the character within the story. The user may then interact with thedisplay (e.g., by double tapping a portion of the display) to return tothe previous position in the story.

In another example use of an electronic device disclosed herein, a usermay be reading an e-book residing on an e-book reader such as the e-bookreader 102 shown in FIG. 1A. In this example, the user is interested infinding all instances in an e-book where a particular character hasdialog. The user may select a graphic for selecting all of thecharacter's dialog. In response to the selection, the electronic textmanager 108 may control a display of the e-book reader 102 to displaydialog metadata provided by the e-book publisher for identifying alldialog attributed to the selected character. In addition, the electronictext manager 108 may control the display to display a navigation controlgraphic including a dynamic semantic timeline of where the character'sdialog appears in the e-book. The user may interact with the controlgraphic for navigating to a portion of the book where specific dialogappears.

FIG. 16 illustrates a message flow diagram of an exemplary operation ofthe system 100 shown in FIG. 1A in accordance with embodiments of thepresent disclosure. Referring to FIG. 16, the e-book reader 102 maycommunicate to the e-book server 106 a request for an e-book (step1600). For example, a user of the e-book reader 102 may view a displayedlisting of e-books available from the e-book server 106. The user mayinteract with the user interface 112 for selecting one of the e-books.In response to the selection, the e-book reader 102 may generate amessage including an identifier of the e-book and may communicate themessage to the e-book server 106 via the network 116. The message mayalso include account information of the user.

The e-book server 106 may receive the message communicated in step 1600.In response to receipt of the message, the e-book server 106 may verifyuser account information for selecting the identified e-book. The useraccount information may be compared with data stored in user accounts130. In an example, the account information may be used for conducting apurchase transaction for the identified e-book. In response to verifyingthe user account information, the e-book server 106 may download thee-book to the e-book reader 102 via the network 116 (step 1602).

The e-book reader 102 may receive the e-book. Subsequent to receipt ofthe e-book, the e-book may be stored in the data store 110. Further, theuser may interact with the user interface 112 to open the e-book forreading. The electronic text manager 108 may display content of thee-book. The user may interact with the e-book by use of the userinterface 112 (step 1604). For example, the interaction may includenon-linear navigation between text subgroups with the electronic text inaccordance with the present disclosure. Data of such interaction withthe e-book may be stored in the data store 110. Further, the electronictext manager 108 may communicate the user interaction data to the e-bookserver 106 (step 1606). In response to receipt of the user interactiondata, the e-book server 106 may infer semantic relation between and linktext subgroups of the e-book in accordance with the present disclosure.The link data may be stored in the data store 120 as metadata 124 forthe e-book for distribution to other e-book readers in accordance withthe present disclosure. The link data may also be provided as it isgenerated to other devices 104 that may already contain pre-distributedcopies of the same e-book.

Some or more of the embodiments disclosed herein, such as for clusteringtext subgroups and creating navigation links between text subgroupsbased on similarity relationships, historical user navigation behaviorand heuristic direct reference-based linking, and the like, may also beapplicable across multiple documents or related e-books. For example, itmay be applied in scenarios in which the documents belong to the sameseries, or are otherwise strongly related to each other (for example,the Harry Potter series). In an embodiment, to achieve this, the textsand other content of each document may be appended in the appropriatesequence to form one large text, and the clustering and linking methodsdescribed above may be applied to the combined text as a whole. Theresulting text clusters, text groups, text subgroups and the navigationlinks between them may be tagged to identify the corresponding documentsthey occur in, and the electronic text manager 108 may store thisinformation along with metadata, such as in the form of a markuplanguage, indicating the boundaries of each constituent document, suchthat when presenting an e-book, only the contents of the e-book beingcurrently used are presented to the user. However, when the user wishesto navigate to a related text subgroup that is located in anotherdocument, the electronic text manager 108 may use this information toaccess the relevant document and present the text subgroup to which theuser has navigated.

When applying clustering to the combined text, it may not be desirablefor clusters to be formed across constituent document boundaries, sincetypically the combined document will not be presented to the user. In anembodiment, clusters may be prevented from forming across constituentdocument boundaries, for example, by applying a very large penalty forcrossing document boundaries. In another embodiment, clusters may beallowed to form across document boundaries, and these clusters may beused for the purpose of creating navigation links, but any such clustersmay be separated at these boundaries when presenting the individualconstituent documents.

Combining multiple texts and processing as a single text, however, mayresult in anomalies, such as, for example, chapter numbers beingrepeated in the combined text. This may result in errors, for instance,when performing heuristic direct reference-based linking As an example,if a sentence in the third book in a series refers to “chapter 2”, itmost probably refers to chapter 2 of the third book, but whileprocessing the combined text, the electronic text manager 108 mayconfuse this reference with the chapters 2 in the first and second bookof the series. To address this problem, in an embodiment, beforecombining the constituent texts into the combined text, the electronictext manager 108 may identify any chapter numbers, section numbers,figure numbers, headings, titles or other such directly reference-ablematerial occurring in each text, tag them with the identifier of thedocument in which they occur, and use the tagged reference-able materialwhen processing the combined text. Tagging may be performed, forexample, using markup methods. If the reference-able material is alreadytagged, the existing tags are updated to include the documentidentifier. Thus, when the electronic text manager 108 applies any ofthe previously discussed methods to the combined text, it may refer tothe document identifier tags and is aware of the corresponding documentin which any given section of the text belongs, and hence is able toresolve references correctly. In an embodiment, while processing thecombined text, the electronic text manager 108 keeps track of theconstituent document to which a current text segment belongs, forexample, by comparing the location of the current text segment with theboundary locations of the constituent documents in the combined text.Subsequently, if a current text segment being processed contains adirect reference, the electronic text manager 108 may assume that thereference is within the context of the document to which the currenttext segment belongs, and hence when creating a navigation link, itlinks to the corresponding directly-reference-able material that istagged with the identifier of the current document. It is noted that thecombining and the tagging is performed mainly for the benefit of theelectronic text manager 108, and may not be presented to the user,especially since the combined document is typically not presented to theuser in the first place.

In an embodiment, when processing references in the combined text, theelectronic text manager 108 may also check whether the directlyreferencing text has any context that further qualifies thereference-able segment (e.g., chapter number, section number or figurenumber) it is referencing, and may use the qualifying information tomore accurately resolve the reference. As an example, if a referencingtext says only “chapter 2,” the electronic text manager 108 may assumeit is a reference to chapter 2 in the same document, but if thereferencing text qualifies it further, such as saying “chapter 2 ofVolume II,” it uses the qualifying information “of Volume II” to moreaccurately identify that the reference is to a chapter in anotherdocument (in this case, “Volume II”). In another embodiment, theelectronic text manager 108 may also use contextual information in thetext surrounding the direct reference to more accurately resolve thereference in the combined text. For example, if the direct reference to“chapter 2”, is in context to “caterpillars becoming butterflies”, theelectronic text manager 108 checks the chapter 2 of each constituentdocument of the combined text to detect a similarity relationship, suchas whether each chapter 2 contains text about caterpillars becomingbutterflies, and may hence create a link to the chapter with thestrongest similarity relationship.

It is noted that processing multiple texts as a single combined text maycreate navigation links between text subgroups across two or moredocuments, some of which may not be available to the user (for example,to a user who has not purchased a particular e-book in a series). Assuch, the electronic text manager 108 may have access to ownershipinformation that specifies the books that the user owns, or otherwisemay have access to (such as through loaning from a friend). Thus, theelectronic text manager 108 may also be aware of the books to which theuser does not have access, but to which some navigation links from thebooks accessible to the user point. When presenting semantic navigationlinks, the electronic text manager 108 may hence filter the links thatpoint to text subgroups in books to which the user does not have access.

In another embodiment, the electronic text manager 108 may determinesuch navigation links, present them to the user and deny the user fromusing them to navigate, but may provide information such as the title,author, cover art, and the like about the relevant document(s) to whichthese links point. In an embodiment, the electronic text manager 108 mayalso provide an interface to purchase or otherwise access the relevantdocument(s) containing the text subgroups to which the links point. Anexemplary interface to purchase the document containing the linked textsubgroup may include a link to one or more online e-book stores that mayhave the document. Another exemplary interface may include a userinterface (UI) element, such as a button, to directly purchase thedocument via the user's credentials stored with one or morepre-determined online e-book stores, for example, by using Amazon.com,Inc.'s 1-CLICK® purchase system. An exemplary interface for othermethods of accessing the linked document, such as by borrowing, mayinclude a list of the users' friends in a social network that own a copyof the linked document and are able to loan it. The user may be enabledto purchase, borrow or otherwise access the whole of the document oronly a part of the document containing the linked text subgroup. Alongwith the interface to purchase, borrow or otherwise access the linkeddocument, the electronic text manager may also include content from thedocument such as text previews, summaries and metadata such as userreviews. The user may be presented with an option to purchase, borrow orotherwise access the document in electronic or e-book form, or as a hardcopy.

It is noted that the text subgroups in external documents pointed to bythe semantic navigation link may in turn contain other semanticnavigation links that point to other text subgroups in other documentsto which the user may not have access. The electronic text manager 108may determine that the user may also prefer to traverse those links, forexample, based on a very strong similarity relationship or semanticrelevance between the corresponding text subgroups, or alternatively,based on historical semantic navigation patterns of other users. In suchcases, the semantic navigation links may be recursively traversed andchained based on similarity relationships and/or historical navigationbehavior, and the resulting list of corresponding documents may bepresented to the user to purchase, borrow, or otherwise access, and theuser may choose to access all or only a subset of the list.

FIG. 17 is a block diagram of the e-book reader 102 shown in FIG. 1Aaccording to embodiments of the present disclosure. Referring to FIG.17, the e-book reader 102 may include a controller 1700 connected to thedata store 110, the electronic text manager 108, the user interface 112,and the network interface 114 by a bus 1702 or similar mechanism. Thedata store 110 may store e-books such as the e-book 118. The controller1700 may be a microprocessor, digital ASIC, FPGA, or the like. In thisexample, the controller 1700 is a microprocessor, and the electronictext manager 108 is implemented in software and may be stored in asuitable memory or data store. The network interface 114 may be a localwireless interface such as a wireless interface operating according toone of the suite of IEEE 802.11 standards, a mobile communicationsinterface, or the like. The user interface 112 may include, for example,a touchscreen, a display, one or more user input components (e.g., akeypad), a speaker, or the like, or any combination thereof.

FIG. 18 is a block diagram of the e-book server 106 shown in FIG. 1Aaccording to embodiments of the present disclosure. Referring to FIG.18, the server 106 may include the processor 126, which is connected tothe data store 120 and the network interface 128 by a bus 1800 orsimilar mechanism. The data store 120 may include the e-book(s) 122, themetadata 124, and the user accounts 130. The processor 126 may beimplemented as software suitably stored in memory and executable by aprocessor. The processor 126 may be configured to implement one or morefunctions described herein. The processor may be a microprocessor,digital ASIC, FPGA, or the like. In this example, the processor is amicroprocessor. The network interface 128 may be a local wirelessinterface such as a wireless interface operating according to one of thesuite of IEEE 802.11 standards, a mobile communications interface, orthe like.

As described earlier, applying these methods to an electronic textresults in metadata specifying text clusters and semantic navigationlinks. In an embodiment, this metadata may be provided within theelectronic text, for example in the form of a markup language. In anembodiment, this metadata may be provided separately from the text, forexample, as records in a separate metadata file, which may enable themetadata to be stored separately from the electronic text. Alternately,for example, the metadata may be provided in part within the electronictext and in part separately from the electronic text. An e-bookprovider, such as an online e-book store, may choose to conditionallyprovide such metadata for an e-book, for example, for a higher price.

In an embodiment, the metadata specifying text clusters and semanticnavigation links for an e-book may be created through manual inputinstead of, or in addition to, the automated methods described above.Such manual input may be provided, for example, by the creators of thee-book, the author, the publisher and/or the editor. Interactive,GUI-based software tools may be used to aid manual input, such asspecifying text cluster boundaries within an electronic text, andcreating semantic navigation links by specifying the text clusters orsubgroups which they link, along with ranking information andsignificant relevant terms for each link. In an embodiment, the metadatacreated by applying the automated methods may be reviewed and edited byhuman input. In another embodiment, the metadata created by human inputmay be used to supplement the metadata created by the automated methods.In another embodiment, the metadata created by human input may be usedto influence the automated methods, and thus, the metadata they create.As an example, in the text clustering method, penalties applied duringclustering may be adjusted based on whether the text subgroups occur atthe boundaries of the clusters in the manually created metadata. Asanother example, semantic navigation links created by the linking methodthat also occur in the manually created metadata may be assigned ahigher rank than other links, even though the automatically determinedsimilarity relationship metrics may indicate otherwise.

The various techniques described herein may be implemented with hardwareor software or, where appropriate, with a combination of both. Thus, themethods and apparatus of the disclosed embodiments, or certain aspectsor portions thereof, may take the form of program code (i.e.,instructions) embodied in tangible media, such as floppy diskettes,CD-ROMs, hard drives, or any other machine-readable storage medium,wherein, when the program code is loaded into and executed by a machine,such as a computer, the machine becomes an apparatus for practicing thepresently disclosed invention. In the case of program code execution onprogrammable computers, the computer will generally include a processor,a storage medium readable by the processor (including volatile andnon-volatile memory and/or storage elements), at least one input deviceand at least one output device. One or more programs are preferablyimplemented in a high level procedural, functional or object orientedprogramming language to communicate with a computer system. However, theprogram(s) can be implemented in assembly or machine language, ifdesired. In any case, the language may be a compiled or interpretedlanguage, and combined with hardware implementations.

The described methods and apparatus may also be embodied in the form ofprogram code that is transmitted over some transmission medium, such asover electrical wiring or cabling, through fiber optics, or via anyother form of transmission, wherein, when the program code is receivedand loaded into and executed by a machine, such as an EPROM, a gatearray, a programmable logic device (PLD), a client computer, a videorecorder or the like, the machine becomes an apparatus for practicingthe presently disclosed invention. When implemented on a general-purposeprocessor, the program code combines with the processor to provide aunique apparatus that operates to perform the processing of thepresently disclosed invention.

While the embodiments have been described in connection with thepreferred embodiments of the various figures, it is to be understoodthat other similar embodiments may be used or modifications andadditions may be made to the described embodiment for performing thesame function without deviating therefrom. Therefore, the disclosedembodiments should not be limited to any single embodiment, but rathershould be construed in breadth and scope in accordance with the appendedclaims.

What is claimed:
 1. A method comprising: determining text subgroupswithin an electronic text; determining a relevance score for each wordof one or more words within each of the determined text subgroups, therelevance score based on at least one of a frequency of occurrence ofthe word within one of the determined text subgroups and a type of theword within one of the determined text subgroups; selecting, by anelectronic device based on input received from a user, a text subgroupfrom the determined text subgroups that corresponds to a current userposition within the electronic text; selecting, by the electronicdevice, a text seed from the selected text subgroup based on therelevance scores of the words within the selected text subgroup;determining a first similarity relationship between the selected textseed and one or more of the determined text subgroups adjacent to theselected text subgroup that do not include the selected text seed;creating a text cluster corresponding to the current user position byassociating the selected text seed with the one or more adjacentdetermined text subgroups based on the determined first similarityrelationship to the selected text seed; determining an activityindication of times when a user has read other determined text subgroupswithin the electronic text; determining a second similarity relationshipbetween the text cluster and other text subgroups; linking the textcluster to at least one of the determined text subgroups based on thedetermined second similarity relationship between the text cluster andthe other determined text subgroups; displaying in a first display area,a portion of the electronic text corresponding to the text cluster; anddisplaying in a second display area, at least one of the determined textsubgroups linked to the text cluster based on the determined times whenthe user read the other determined text subgroups.
 2. The method ofclaim 1, wherein one or more of the linked determined text subgroups aresorted by a similarity score based on the determined similarityrelationship.
 3. The method of claim 1, comprising displaying a graphicas an indicator of the determined similarity relationship in an areaadjacent to the display area for each determined text subgroup linked tothe text cluster.
 4. The method of claim 1, wherein displaying in thesecond display area comprises displaying in the second display area, oneor more of the linked determined text subgroups positioned before thetext cluster.
 5. The method of claim 1, wherein displaying in the seconddisplay area comprises displaying in the second display area, one ormore of the linked determined text subgroups positioned after thecurrent text cluster.
 6. The method of claim 1, wherein determining thefirst or second similarity relationship comprises one of performingsemantic analysis, performing natural language processing, identifyingcausal relationships between the text seed and the text subgroups,determining semantic similarity based on ontology, using a semanticindex to compare semantic similarities, and determining a statisticsimilarity.
 7. A method comprising: determining text subgroups within anelectronic text; determining a relevance score for each word of one ormore words within the determined text subgroups, the relevance scorebased on one of a frequency of occurrence of the word within one of thedetermined text subgroups and a type of the word within one of thedetermined text subgroups; selecting, by an electronic device, a textsubgroup from the determined text subgroups that corresponds to acurrent user position within the electronic text; selecting, by theelectronic device, a text seed within the selected text subgroup basedon the relevance scores of the words within the selected text subgroup;determining a first similarity relationship between the selected textseed and one or more of the determined text subgroups adjacent to theselected text subgroup that do not include the selected text seed;creating a text cluster by associating the text seed with the one ormore adjacent determined text subgroups based on the first similarityrelationship; and for each of the determined text subgroups outside ofthe text cluster: determining an activity indication of time when a userhas read the determined text subgroup; determining a second similarityrelationship between content of the determined text subgroup and thetext cluster; and linking the determined text subgroup to the textcluster based on the second similarity relationship and on thedetermined time the user read the text subgroup.
 8. The method of claim7, wherein determining the first similarity relationship comprisesdetermining the first similarity relationship between one of thedetermined text subgroups and one or more adjacent determined textsubgroups based on another similarity relationship of content withineach determined text subgroup.
 9. The method of claim 7, whereindetermining the first similarity relationship comprises determining thefirst similarity relationship between one of the determined textsubgroups and one or more adjacent determined text subgroups based onone of chapters, paragraphs, and sentences of the electronic text. 10.The method of claim 7, wherein linking the determined text subgroup tothe text cluster comprises storing a navigational aid in metadata of theelectronic text that indicates association of the determined textsubgroup with the text cluster.
 11. The method of claim 10, furthercomprising presenting, for each linked determined text subgroup outsideof the text cluster, a navigational link that links the linkeddetermined text subgroup to the text cluster.
 12. The method of claim 7,wherein determining the second similarity relationship comprisesdetermining the second similarity relationship between the text clusterand the determined text subgroups positioned forward of the textcluster, and wherein linking comprises linking the text cluster to theforward-positioned determined text subgroup having the highest secondsimilarity relationship.
 13. The method of claim 7, wherein determiningthe second similarity relationship comprises determining the secondsimilarity relationship between the text cluster and the determined textsubgroups positioned backward of the text cluster, wherein linkingcomprises linking the text cluster to the backward-positioned determinedtext subgroup having the highest second similarity relationship.
 14. Themethod of claim 7, wherein determining the second similarityrelationship comprises: using a semantic graph representing relationsbetween words to compare words of the text cluster and words in thedetermined text subgroup; and using the comparison to link thedetermined text subgroup with the text cluster.
 15. The method of claim14, further comprising generating the semantic graph using at least oneof pre-generated summarization of the electronic text, metadata of theelectronic text, semantic analysis of the electronic text, semanticindexing, natural language processing (NLP), and statistical techniques.16. An electronic device comprising: a hardware processor; an electronicdocument manager configured to: determine text subgroups within anelectronic text; determine a relevance score for each word of one ormore words within the determined text subgroups, the relevance scorebased on one of a frequency of occurrence of the word within one of thedetermined text subgroups and a type of the word within one of thedetermined text subgroups; select, based on input received from a user,a text subgroup from the determined text subgroups that corresponds to acurrent user position within the electronic text; select, a text seedfrom the selected text subgroup based on the relevance scores of thewords within the selected text subgroup; determine a first similarityrelationship between the selected text seed and one or more determinedtext subgroups adjacent to the selected text subgroup that do notinclude the selected text seed; create a text cluster corresponding tothe current user position by associating the selected text seed with theone or more adjacent determined text subgroups based on the determinedfirst similarity relationship to the selected text seed; determine anactivity indication of times when a user has read other determined textsubgroups within the electronic text; determining a second similarityrelationship between the text cluster and other determined textsubgroups link the text cluster to at least one of the determined textsubgroups based on the determined second similarity relationship betweenthe text cluster and the other determined text subgroups; and a userinterface configured to: display in a first display area, a portion ofthe electronic text corresponding to the text cluster; and display in asecond display area, at least one of the determined text subgroupslinked to the text cluster based on the times when the user read theother determined text subgroups.
 17. The electronic device of claim 16,wherein one or more of the linked determined text subgroups are sortedby a similarity score based on the determined similarity relationship.18. The electronic device of claim 16, wherein the user interface isconfigured to display a graphic as an indicator of the determinedsimilarity relationship in an area adjacent to the display area for eachdetermined text subgroup linked to the text cluster.
 19. The electronicdevice of claim 16, wherein the electronic document manager isconfigured to determine the first or second similarity relationship byone of performing semantic analysis, performing natural languageprocessing, identifying causal relationships between the text seed andthe text subgroups, determining semantic similarity based on ontology,using a semantic index to compare semantic similarities, and determininga statistic similarity.
 20. An electronic device comprising: a hardwareprocessor; an electronic document manager configured to: determine textsubgroups within an electronic text; determine a relevance score foreach word of one or more words within the determined text subgroups, therelevance score based on one of a frequency of occurrence of the wordwithin one of the determined text subgroups and a type of the wordwithin one of the determined text subgroups; select, a text subgroupfrom the determined text subgroups that corresponds to a current userposition within the electronic text; select, a text seed within theselected text subgroup based on the relevance scores of the words withinthe selected text subgroup; determine a first similarity relationshipbetween the selected text seed and one or more of the determined textsubgroups adjacent to the selected text subgroup that do not include theselected text seed; create a text cluster by associating the text seedwith the one or more adjacent determined text subgroups based on thefirst similarity relationship; and for each of the determined textsubgroups outside of the text cluster: determine an activity indicationof time when a user has read the determined text subgroup; determine asecond similarity relationship between content of the determined textsubgroup and the text cluster; and link the determined text subgroup tothe text cluster based on the second similarity relationship and on thedetermined time the user read the determined text subgroup.
 21. Anon-transitory computer-readable storage medium having stored thereoncomputer executable instructions for performing the following steps:determining text subgroups within an electronic text; determining arelevance score for each word of one or more words within each of thedetermined text subgroups, the relevance score based on at least one ofa frequency of occurrence of the word within one of the determined textsubgroups and a type of the word within one of the determined textsubgroups; selecting, by an electronic device based on input receivedfrom a user, a text subgroup from the determined text subgroups thatcorresponds to a current user position within the electronic text;selecting, by the electronic device, a text seed from the selected textsubgroup based on the relevance scores of the words within the selectedtext subgroup; determining a first similarity relationship between theselected text seed and one or more of the determined text subgroupsadjacent to the selected text subgroup that do not include the selectedtext seed; creating a text cluster corresponding to the current userposition by associating the selected text seed with the one or moreadjacent determined text subgroups based on the determined firstsimilarity relationship to the selected text seed; determining anactivity indication of times when a user has read other determined textsubgroups within the electronic text; determining a second similarityrelationship between the text cluster and other determined textsubgroups; linking the text cluster to at least one of the determinedtext subgroups based on the determined second similarity relationshipbetween the text cluster and the other determined text subgroups;displaying in a first display area, a portion of the electronic textcorresponding to the text cluster; and displaying in a second displayarea, at least one of the determined text subgroups linked to the textcluster based on the determined times when the user read the otherdetermined text subgroups.
 22. A non-transitory computer-readablestorage medium having stored thereon computer executable instructionsfor performing the following steps: determining text subgroups within anelectronic text; determining a relevance score for each word of one ormore words within the determined text subgroups, the relevance scorebased on one of a frequency of occurrence of the word within one of thedetermined text subgroups and a type of the word within one of thedetermined text subgroups; selecting, by an electronic device, a textsubgroup from the determined text subgroups that corresponds to acurrent user position within the electronic text; selecting, by theelectronic device, a text seed within the selected text subgroup basedon the relevance scores of the words within the selected text subgroup;determining a first similarity relationship between the selected textseed and one or more of the determined text subgroups adjacent to theselected text subgroup that do not include the selected text seed;creating a text cluster by associating the text seed with the one ormore adjacent determined text subgroups based on the first similarityrelationship; and for each of the determined text subgroups outside ofthe text cluster: determining an activity indication of time when a userhas read the determined text subgroup; determining a second similarityrelationship between content of the determined text subgroup and thetext cluster; and linking the determined text subgroup to the textcluster based on the second similarity relationship and on thedetermined time the user read the determined text subgroup.